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I have installed a TREMECTR-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 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. Thereare some pic here to show a GM TKO next to a Muncie 4sp. Unlike theRichmond 5 speed, the TREMEC is a true "overdrive" transmission and assuch may preclude a required change of gearing in the rear-end. Ifyou already have a low rear-end gear, then you'll be especially happy witha TREMEC 5sp. 5th gear is available in a .68 or .83 ratio!

This is a version of the TREMEC TKO modified for installation in GMcars. Forte's replaces the Ford input shaft with a GM compatible versionthat is supplied by TREMEC. He installs the GM input shaft, machinesdown the input shaft bearing retainer, elongates bellhousing bolt holes,drills for the TH400 transmission mount, and machines off the rear torquearm bosses. As of mid-'2003 or so, TTC is now making the GM TKOswith 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 stockcomponents in front of the transmission (ie bellhousing, clutch, shifterlinkages, etc). Even the stock crossmember and TH400 transmissionmount can be used without modification, which is detailed later in thisarticle. And yes, you can use a Lakewood (SFI approved) scatter shieldbellhousing (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 slipyoke installed, and shorten your driveshaft by about 2".

The TREMEC shifter is a "top loader", meaning that the shifter protrudesout of the top of the transmission. You can see this in several of thepics shown below. In comparison, the Richmond, Muncie and Saginaw transmissionshave 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 Pro5.0shifter Any Hurst shifter bar will bolt up to the shifter (using8mm metric bolts though). We recommend that you use the stock shifterthroughout the break-in period, then decide if you really need a new oneafter 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 ofthe transmission, and as such will not aid in clearance problems with thefloor pan tunnel. For more details on the various shifter locations,please see here (

For more details (gear ratios, options, schematic, additional availableparts, etc), please see

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Driver side viewPassenger side view

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

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View of the top. Note the 2 rectangular plates. These are optionalshifter 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 (TREMECrelated), and of course Chevellabration in Nashville, TN! TheTREMEC is working out great! First gear is plenty low, and fifthis plenty high! AT 60mph, the engine is turning about 1900rpm (4.33 rear-end gear, 31.5" tall tires).

The Tunnel (originally an automatictransmission 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 ofthe 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 (\lower_tailshaft.html)
This is covered in detail below.

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Notice that the shifter base protrudes up through the floor quite aways. I thought it would be very difficult to remove the transmissionwithout 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 removethis section, and slide the transmission back for removal. In thepic 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 outpretty easily.

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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, withthe top of the trans protruding through the floor. Here aresome additional pics (\tunnelsurgery.html)
You can see in the following pics it is a tight fit.

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Pic on the left shows the top corner of the trans hitting the tunnel; passengerside. Pic on the right shows the top corner of the trans hittingthe 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. Thesewere the first points to hit the tunnel. Again, I used the 4" hand grinderwith a cutting wheel.

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The Tunnel (originally a floor shift manual transmissioncar):

I don't have direct experience with the floor shift manual transmissiontunnel, 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 beelongated 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;

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

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I did move it rearward a couple of inches though (and I now have bluebucket 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

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

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

The stock 307/Powerglide crossmember bolts up to the transmisison mountok, except for one problem. The bottom of the tailhousing is shapedsuch 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 removedfor you!

The stock TH350 crossmember will work without modification. Thisis 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) mountingholes on the frame. Note the I had to elongate the 3rd hole a bit.No big deal.

Rear of car
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Front of car

Transmission Mount:

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

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

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To remedy the situation, I cut the lower section of the tailhousingoff. 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 foryou free of charge.

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. And click here to see Centerforce's instructions; Technology Electronic device

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

Don't forget a driveshaft loop. NHRA rules specify it should be6" 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 custommake one as I did. I chose to weld the top half of the front loopto the floor bracing, and bolt the lower half of the loop to the upperhalf. In the pic below, the front driveshaft loop is in the foreground,the rear loop in the middle, and the pinion at the back.

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Misc Pictures:

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From Driver's sideAnother view from Driver's side.


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