1966 impala - Impala Tech
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post #1 of 4 (permalink) Old 03-25-2012, 12:39 AM Thread Starter
Join Date: Mar 2012
Location: Michigan
Posts: 7
Smile 1966 impala

okay I have a 66 impala that has a 2 speed powerglide I got a 700 r 4 I want to put in I bought the aftermarket cross member how many inches do I need to cut off the driveshaft and it is the original yolk going to work on the 700 r 4 or what other modifications do I need to do to make this work somebody please give me a solution thanks and have a great day
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post #2 of 4 (permalink) Old 03-25-2012, 10:06 AM
Join Date: Aug 2008
Location: Miamisburg, Oh.
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I don't have your info but I can tell you that it's been discussed on here quite a few times, you might want to try the Search function while you're waiting for a reply.

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post #3 of 4 (permalink) Old 03-25-2012, 10:34 AM
Join Date: Jan 2006
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You measure for the correct drive shaft length. There is no gaurantee of a correct fit other wise as the length changes with the ride height (some people actually enjoy scraping over every speed bump in the road and make their cars lower than stock). If you don't know how to measure for a drive shaft Denny's Drive Shaft has a page that explains the procedure:


As to the rear yoke, it uses the same 27 spline out put shaft that the PowerGlide, the TH350, the manual three speed, and the manual four speed (both the Muncie and the Borg-Warner T-10) do. Only the TH400 and the new manual four and five speeds use the larger stronger 31 spline out put shaft and front yoke.

You have an aftermartket transmission cross-member so that will acount for the mount being moved to the rear (because of the extra fourth gear in the TH350 case that turns a TH350 into a 700R4) so that won't be an issue. All you need now is linkage to find those two extra gears (longer rods) and a gear selector plate to go in the dash (or on your console) so that you know what gear you are in. That assumes you want it to look stock. If your are going for the ProMod look you just bolt a ratcheting Hurst reverse lock out shifter on the floor and drill a hole for the cable to go through.

The last and most critical thing to do has to do with the TV adjustment. Get this wrong and you will be buying another 700R4 transmissin inside of a day or less. You need a sturdy (not cheap) mounting bracket to secure the cable. If you have a Rochester carburetor youi are in luck as there are literally millions of good stock ones in salvage yards waiting to be picked up. If you have a Holley or a Carter (aka Edelbrock) carburetor then you have to buy an expensive strong (you are standing on this part) bracket to keep the cable end where it needs to be.

A bracket is only half of the problem. The Holley or Edelbrock carb doesn't use a Chevrolet throttle arm. This is because Chevy didn't use a 700R4 with Holley, only a manual trans or a TH400; and because Chrysler (MOPAR) used Carter carbs as their stock carb (The Holley has Ford throttle arm because Ford sourced Holley as their OEM carb vendor). That means you have to modify the throttle arm to make it work with a 700R4.

Here is a web site or two that explain this issue.


This bracket only allows the throttle to bolt up but can be modified:


Here is someone talking about the brackets

Big Dave
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post #4 of 4 (permalink) Old 03-25-2012, 08:48 PM Thread Starter
Join Date: Mar 2012
Location: Michigan
Posts: 7
thank you guys for all the help but I still don't know how many inches need to be cut off the driveshaft my car ride in a regular height stock height and I'm really not sure how to measure a drive shaft if somebody who has done this before to a 66 in pile up please give me a direct measurements I've heard 3 inches or 2.75 and once again thanks to everybody gave me the good advice have a great night and god bless
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