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Discussion Starter · #1 ·
I git a 67 Chevelle with a 350 that we took the powerglide of and put in a turbo 350. Now my rpm is running at 3000 going 70 mph. Did a quick check on the rear gears that turned out to be 355. What tranny can I get that will calm my engine down with out doing anything to the rear gears?
 

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Both trannys have a 1 to 1 final ratio so the rim wouldn't change unless your converter is slipping. You'll need a overdrive like a 700r4 or 200r4 to slow your motor down
 

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A 200-4R (overdrive automatic) will bolt in right where your existing transmission is without having to shorten the driveshaft.

You will have to move the transmission crossmember backwards about 6" and (probably) drill a pair of holes in the frame to attach the crossmember it's new location.

You will have to connect the TV cable properly to the carburetor and make sure it is adjusted correctly (many, many articles on this.)

If you want the torque converter lockup function to be enabled, you will need to hook up a switch for this (vacuum switch, manual switch, pressure switch, etc. - again, many, many articles on this and many ways to do it.)

You will have to change or modify the shifter so that you can shift the transmission properly to get to all 4 gears as well as park, reverse and neutral.

You will also need a new torque converter (different than the TH350.)

That is, for the most part, all you have to do to swap a 200-4R in where a TH350 is.
 

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What do you use the car for ?

Street only

Strip only

Street / Strip combo

Street / Road Racing

As said by Jim Mac and Steve a TH2004R would result in NO change to the Driveshaft,
just move the Trans Cross member back and drill 2 holes
install the TH2004R with a new LockUp Converter
 

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Changing rear gear sounds like what you want. could throw on a Gear Vendor over drive but would have to cut or get new drive shaft... be careful with the 200R4 TV cable....
 

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What was your RPM at 70 with the powerglide?
As JimMac said, both the powerglide and the turbo 350 have a 1-1 final ratio, so your engine rpm at 70 should not have changed from the glide to the turbo 350.
May seem like a silly question, but are you sure the 350 trans getting into third gear?
What size rear tires?
I went with the 700R4 trans and it is a very tight fit in the trans tunnel of my '66.
It will vary a lot, but you will probably be out somewhere from $750 to $1,500 or more to buy new gears and change them out, versus the cost of an overdrive auto like 200 or 700.
 

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3000 is right with a 27 in. tire. You need OD or different gears.
 

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Discussion Starter · #13 ·
did a quick check with the rear end. It went 1.75/1 full round on the 14" tire. I am guessing the gears are 355, if so it would just make sense to change out the gears to 308
 
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