(this page was last updated on 1/17/2004)
TrREMEC GM TKO 5 speed manual transmission
installation notes
1969 Chevelle
(should apply to all GM '68-'72 A-Body cars)
I have installed a TREMEC TR-3550 TKO 5 speed manual transmission into my '69 Chevelle.  Below are the details of my experiences.  Unless otherwise noted, all comments in this article refer the GM '68-'72 GM A-Body cars.

If you're interested in buying a TREMEC transmission, please check out 5SpeedTransmissions.com.  I am now a distributor for Forte's Parts Connection.

Table of Contents:
About the Transmission
The Tunnel
Driveshaft angle
Transmission Mount
TR-3550 TKO vs TR-3550
Proper Break-in Procedure
About the Car
Where to Buy a Tremec

About the GM TKO transmission:
TREMEC transmissions are typically used in Ford applications.  They are more square in shape than a typical GM transmssion (see pics below) and are a toploader shifter configuration. There are some pic here to show a GM TKO next to a Muncie 4sp. Unlike the Richmond 5 speed, the TREMEC is a true "overdrive" transmission and as such may preclude a required change of gearing in the rear-end.  If you already have a low rear-end gear, then you'll be especially happy with a TREMEC 5sp.   5th gear is available in a .68 or .83 ratio!

This is a version of the TREMEC TKO modified for installation in GM cars. Forte's replaces the Ford input shaft with a GM compatible version that is supplied by TREMEC.  He installs the GM input shaft, machines down the input shaft bearing retainer, elongates bellhousing bolt holes, drills for the TH400 transmission mount, and machines off the rear torque arm bosses.  As of mid-'2003 or so, TTC is now making the GM TKOs with the exact same specs as the modified TKOs that Forte was selling.

This transmission (TKO) is advertised to handle 525ft/lb of torque; more than the Richmond 5 speed (425ft lb).

Even though this is a Ford style transmission, you can use all stock components in front of the transmission (ie bellhousing, clutch, shifter linkages, etc).  Even the stock crossmember and TH400 transmission mount can be used without modification, which is detailed later in this article.  And yes, you can use a Lakewood (SFI approved) scatter shield bellhousing (strongly recommended).

This transmission does NOT require a hydraulic clutch.

Since the output is a Ford C6 output, you'll need to have a TKO slip yoke installed, and shorten your driveshaft by about 2".

The TREMEC shifter is a "top loader", meaning that the shifter protrudes out of the top of the transmission. You can see this in several of the pics shown below. In comparison, the Richmond, Muncie and Saginaw transmissions have the shifter mounted on the side.

The stock shifter that comes with the TREMEC is a pretty good shifter, however a performance shifter is nice if you prefer a higher quality shifter. I upgraded to the Pro5.0 shifter  Any Hurst shifter bar will bolt up to the shifter (using 8mm metric bolts though).  We recommend that you use the stock shifter throughout the break-in period, then decide if you really need a new one after driving if for a while.

Gear ratios are as follows:
1st = 3.27  2nd = 1.98   3rd = 1.34   4th = 1.0  5th = .68  (with an optional .83)
For comparison, the Richmond has a 1:1 5th gear.

At the time of purchase, it's possible to have the shifter location "relocated" to 7 other positions! I'm am using the "stock" rearward position. Changing the shifter location will not change the physical dimensions of the transmission, and as such will not aid in clearance problems with the floor pan tunnel.  For more details on the various shifter locations, please see here (http://www.5speedtransmissions.com/new_gm_shifter.html)

For more details (gear ratios, options, schematic, additional available parts, etc), please see http://www.5speedtransmissions.com.

Click to see a larger version of this pic    Click to see a larger version of this pic

         Driver side view                                                                Passenger side view

A.  Reverse light switch:  Sensor in main case on driver's side
B.  Speedometer:   A GM style unit is available
C.  Servo wire:  Neutral switch, usually used for computer-equipped vehicles

Click to see a larger version of this pic

View of the top.  Note the 2 rectangular plates.  These are optional shifter mount locations.

Progress so far (1/10/04):

The car is 95% done and I have driven it about 100 miles now.  It's attended 2 Super Chevy events as a display car in vendor booths (TREMEC related), and of course Chevellabration in Nashville, TN!   The TREMEC is working out great!  First gear is plenty low, and fifth is plenty high!   AT 60mph, the engine is turning about 1900 rpm  (4.33 rear-end gear, 31.5" tall tires).

The Tunnel (originally an automatic transmission car):

Since everyone is most interested in how the TREMEC fits in the tunnel, I'll start there.

I initially attemped to install the trans without serious cutting of the tunnel, and I dropped the tailshaft of the trans down so it would fit.  This is NOT a good idea, see more about why here (http://www.5speedTransmissions.com\lower_tailshaft.html )
This is covered in detail below.


Notice that the shifter base protrudes up through the floor quite a ways.  I thought it would be very difficult to remove the transmission without dropping the trans way down while still bolted to the engine.  So I cut the section right behind the shifter base, welded on some tabs, and screwed it back on from the bottom.  This will allow me to remove this section, and slide the transmission back for removal.  In the pic below, note the black area just behind the shifter base.  In retrospect, I don't think it's necessary to do this step.  The trans comes out pretty easily.

Since I found out the hard way about the cons of lowering the driveshaft, I've since raised the tailshaft as high as possible in the tunnel, with the top of the trans protruding through the floor.   Here are some additional pics (http://www.5speedTransmissions.com\tunnelsurgery.html)
You can see in the following pics it is a tight fit.

Click to see a larger version of this pic    Click to see a larger version of this pic

Pic on the left shows the top corner of the trans hitting the tunnel; passenger side.  Pic on the right shows the top corner of the trans hitting the tunnel; driver side.

To make the trans fit a little better, I cut off 3 unnecessary 'tabs'.  Note the black magic marker marks on the following 2 pics.  These were the first points to hit the tunnel. Again, I used the 4" hand grinder with a cutting wheel.


The Tunnel (originally a floor shift manual transmission car):

I don't have direct experience with the floor shift manual transmission tunnel, but I've been told that the TREMEC fits better in this application.  And I've been told that the existing shifter hole will only have to be elongated on 2 sides!

The Tunnel; other cars:

The '67-'81 Camaros/Firebirds do not require any additional 'surgery' to the transmission tunnel, other than to get the shifter base through.

There is a list of cars, and some installation details on this page; http://www.5speedtransmissions.com/tr-3550.html

Stock Center Console:
The stock console will work just fine!   See additional some pics here.

I did move it rearward a couple of inches though (and I now have blue bucket seats!).    Mike Forte, Forte's Parts Connection, is working on a new custom shifter just for the GM console applications.  Please watch for details at http://www.5speedtransmissions.com.

Driveshaft Angle:
It's reasonably important to get your driveline angles set up right.   A call to Patterson Driveshaft in Indianapolis was very imformative.  They suggested that as long as location of where the pinion angle meets the transmission-driveshaft angle crosses is not in the middle of the driveshaft, I should not experience any problems.  I'll work on a diagram for this.
My final transmission to driveshaft angle is about 5 degrees, and my pinion angle is 2 degrees.

Here's plenty of links to keep you busy reading up on driveline angles!

The stock 307/Powerglide crossmember bolts up to the transmisison mount ok, except for one problem.  The bottom of the tailhousing is shaped such that it interferes with the crossmember and it won't clear.  To correct the problem, remove the torque arm boss as shown below.  Or, if you're ordering a new GM TKO from us, then ask for it to be removed for you!

The stock TH350 crossmember will work without modification.  This is also true of the '66/'67 GM A-body TH350 crossmembers  (PG, M20, M21 used the TH350 crossmember).

The crossmember is bolted to the 5th and 3rd (from the front) mounting holes on the frame.  Note the I had to elongate the 3rd hole a bit.  No big deal.

Rear of car Click to see a larger version of this pic Front of car

Transmission Mount:

The stock TH400 transmission mount works perfectly. It bolts right up.

Click to see a larger version of this pic

However, the casting of the TREMEC interferes with the original crossmember.

Click to see a larger version of this pic    Click to see a larger version of this pic

To remedy the situation, I cut the lower section of the tailhousing off.  I used a 4" hand grinder with a cutting disk.
Again, if you're ordering a new GM TKO from us, we can remove it for you free of charge.


It is always recommended that you index the bellhousing, regardless of transmission used.  This involves getting the pilot bearing on the crankshaft lined up with the input shaft on the transmission.  Click here to see Lakewood's instructions.   And click here to see Centerforce's instructions; page 1, page 2.

The shifter bar bolt holes are threaded just like a Hurst shifter, except that they are metric;  8mm.

Don't forget a driveshaft loop.  NHRA rules specify it should be 6" from the front universal joint using 1/4" thick by 2" wide flat stock.  You can purchase one for about $30.00, or less than $5.00 you can custom make one as I did.  I chose to weld the top half of the front loop to the floor bracing, and bolt the lower half of the loop to the upper half.  In the pic below, the front driveshaft loop is in the foreground, the rear loop in the middle, and the pinion at the back.

Click this pic to see a larger version

Misc Pictures:


             From Driver's side                                                       Another view from Driver's side.
TR-3550 TKO vs TR-3550:
The only difference that I know of between the 2 versions is the output shaft.  The TKO unit is stronger, handling up to 100ft/lbs more than the non-TKO version.  There is also a TKOII version, typically used by road racers.  It's rated at about 50 ft/lbs more torque, but has a 0.83 5th gear.  The 3rd gear material is also upgraded.

Unfortunately, TREMEC doesn't ship much of anything in regards to documentation about the transmission.  I hoped to see a booklet or something to document the various sensors, rubber plugs, parts list, schematic, output size, etc.  There was a small sheet of paper which indicated what fluid to use and how much.

Here's the information that I received with the transmission:

    Oil Recommended:   GM Synchromesh, GM part number 12345349 (3 quarts).  Optional fluids are Dexron II E and Mercon Synthetic.

    Clutch:  In order to maintain correct clutch adjustments, an adjustable clutch cable/quadrant kit is recommended.  This will prevent hard shifting, gear clash, and premature wear of the synchronizer rings.

    Transmission gear rattle may be heard under heavy loads at low speed, during cancellation, in neutral, and sometimes under wide open throttle.

    Mis-calibration of the clutch-driven plate or the crankshaft balancer may be the cause.  Usually, no cost-effective correction is available.

    Shift Lever:   Backward installation will give you an awkward, long reach.

    If the upper shift lever is installed without the rubber isolator or with a modified shifter lever, the transmission will sound very noisy.

    Use of any aftermarket shifter may result in gear noise or gear failure.

There is tons of additional information at http://www.5speedTransmissions.com.

Warranty Information:
Tremec does not offer a warranty.  We will will handle any claims you have on a "case by case" basis.
There is also an extended warranty available for $500, but it's obviously very pricey.


  • Use the stock shifter for the break-in period.  Then, replace with a better shifter if desired.

  • If you have a Ford, you might consider looking at the Clutch Quadrant designed by Forte's Parts Connection.  See it at http://www.fortesparts.com/quadrant.html.  This will improve how well your clutch works, and Ford's are known for not disengaging well.   Also, for racing, I'd strongly recommend upgrading to the Pro5.0 shifter.

    Don't forget, proper shifting is essential for longevity, just like any other manual transmission.

  •  There is a 'tab' hanging off the bottom of the transmission at the front of the tailhousing. The following pics shows the tab. It could get caught on a high spot in the road  (RR crossing, speed bump, etc), which could cause some major damage.  I know of one person who had this happen.   Thanks to Mike Harrigan for the suggestion.
    Click to see a larger version of this pic
  • If you want to take the previous suggestion one step farther, you could fabricate a mini 'skid plate' that would bolt right to the tailhousing bolts.  This would help prevent the trans from getting caught on anything.   This suggestion might be more useful for a low sitting car.  Again, thanks to Mike Harrigan for the suggestion.
Proper Break-In Procedure :
  • Put 3qt of good quality ATF (Auto Transmission Fluid) (Dexron) into the transmission. Pour in through shifter mount, or through one of the top plates.  You can use the fill plug on the side of the transmission also (afterall, that's what it's for!).  It's just easier to pour it in from the top if you can.
  • Put car on jacks, run the transmission up and down through all gears repeatedly for 15 minutes.  This will allow the gears to break in properly.
  • After 500-700 miles, drain the ATF, and put in 3qt of the GM Synchromesh fluid,  the part number is 12345349. If it's a race car only, then switch to the GM Synchromesh after the initial break-in.
  • Don't use synthetic lube for 6000-8000 miles.  In fact, we don't recommend synthetic, just stick with the GM synchromesh.
Purchase price:
For $2126.00, I got the TREMEC TR-3550 TKO 5 speed transmission, shifter base, 1330 series C6 small seal 31 spline slip yoke, reverse light switch, and a speedometer cable adapter. This price included shipping/handling charges.
For current prices, see this page: http://www.5speedTransmissions.com/gm_3550_package.html

What about the car?
It's a '69 Malibu pro-street car.  It has been back-halved and sports a ladder bar suspension, a Ford 9" rear-end with disk brakes, 15x15 Weld Prostars with 31x18.5 Mickey Thompson Sportman tires, 15 x 6" Weld Prostars, 500hp/500 ft. lb 468 BBC, and a 5" cowl induction hood, NASCAR stock car exhaust tips, ghosted Bowtie with flames on the side of the car.  All other components on the car are pretty much stock.  My best friend and I have done all of the work, except for the body work.  You can see pics of my car and more information at www.ProStreetCar.com.  It's the blue '69.

Where to buy a TREMEC 5 or 6 speed?
If you're interested in buying a TREMEC transmission, please check out 5SpeedTransmissions.com.  I am now a distributor.  There's quite a lot of information about the TREMEC at this website, as well as prices, accessories, etc.

Thanks to Wes. Vann for helping with the writing and publishing.
Thanks to Team Chevelle for hosting this article.

Thanks to Mike Forte for providing information.
Forte Parts Connection
376 Cambridge Street
Burlington, MA 01803
Ph:  781-273-9900
Fax: 781-273-9955

Patterson Driveshaft, Indianapolis IN  (317) 481-0495 or toll free at (877) 836-5334

Author:  Mike Pell
Website:   www.5SpeedTransmissions.com
Originally published in February 2001

The end.