Author Topic: 700 R transmission swap  (Read 196 times)

Offline Smitty31

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700 R transmission swap
« on: October 27, 2018, 03:21:23 PM »
I have a 1979 gmc high sierra 4x4. Engine is a 350 transmission is a 400 turbo. Will a 700 R from a 1992 chevy pickup 4x4 work in my truck
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Offline Captkaos

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Re: 700 R transmission swap
« Reply #1 on: October 27, 2018, 07:02:12 PM »
You will have to come up with a transfer case adapter and transfer case as the 92 model won't work with your transfer case and adapter..

Offline Smitty31

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Re: 700 R transmission swap
« Reply #2 on: October 28, 2018, 10:56:26 AM »
Thanks for the info. What year will work with my 79. Or is there a year that will work.
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Offline 1967KaiserM715

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Re: 700 R transmission swap
« Reply #3 on: October 29, 2018, 06:17:22 PM »
Any 4x4 700r4 should be a 27 spline output shaft, a TH400 would have a 32 spline output shaft.

So that means no matter what you do you need a NP208 or a NP241C passenger side drop that is a 27 spline input.

The transmission to transfer case adapter from a 92 could work, there may need to be an adapter to mount the tail mount support to, or even a new transmission cross member.

A complete drop in system could be had from a 1982 to 1991 square-body truck. Remember 1988-1991 was a dual year that had both square-body and the GMT400(1988-1998 style)

The best 700r4 case are typically found in 1985 and later trucks, there are also several internal upgrades that outperform earlier transmissions.
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1975 Beetle(not running) 1985 Mercedes 300D(not running) 1952 M35    1967 M715(not running)
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Offline Irish_Alley

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Re: 700 R transmission swap
« Reply #4 on: October 30, 2018, 08:13:58 AM »
cheapest way about this is to find a donor truck. you not only need the trans and transfer case but also driveshafts and you might need the cross member also. try to find a donor the same setup as your (i.e long bed for long bed or short bed for short)
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