700R4 transmission interchange

700R4 transmission interchange

Postby ally_g [OP] » January 2nd 2011, 1:37am

Would like to know if a rebuilt 700R4 transmission from a 1985 Chevrolet pick up truck, 2 wheel drive, will fit into my 1988 GMC Safari van RWD which has the 700R4 transmission ? Have looked at the rebuilt transmission and it looks the same as what is in the van.
Would the speedometer driven gears be the same ? I realise that there are different speedometer ratios/gears as indicated by their color along with gear tooth counts.
Advice and recommendations appreciated.
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Re: 700R4 transmission interchange

Postby Phantom » January 2nd 2011, 1:50am

It should fit with no problem , the speedometer gear may or may not be the same , but you can swap them so you can keep the original in your van
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Re: 700R4 transmission interchange

Postby cowboydan » January 2nd 2011, 4:49am

another difference you might want to check on is the tail shaft length.
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Re: 700R4 transmission interchange

Postby ally_g [OP] » January 2nd 2011, 6:40am

Thank you.
The speedometer driven gear I believe broke some time ago,(speedometer quit working) so the original one from the van would have to be replaced if the one in the rebuilt transmission is different.
The tail section/tube is the exact same length, so that is not an issue.
While waiting for replies to this post I went onto a few other sites to find answers. One site has people saying something about a lockout harness needing to be modified. While another refers to a lock out kit for the converter.From what I read somewhere on this site, there was some mention of the OBD1 and OBD2 With both vehicles being manufactured before 1996 they would both fall into the OBD1 category. So, I do not understand why this other site is trying to say a lockout kit is necessary. Both transmissions are 700R4 without the electronics.I mean, both have the TV cable and the other connections. I am wondering if they are confusing something pertaining to interchanging an electronic transmission and a 700R4 that has the TV cable.
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Re: 700R4 transmission interchange

Postby Gary » January 2nd 2011, 8:54am

The tranny I am using for my Ole Yellar V8 swap was in a 1989 donor V8 Astro and is from a 1991 V8 truck.The advantage is the V8 trannies do have a better clutches.The tranny fit in the running donor and worked fine.I am suggesting that you do a upgrade with a Trans-go shift kit,vett servo,and a .5 boost valve.These are not hard to do if you follow the directions and the costs aren't too bad either.A tranny cooler should be on your shopping list as well either way.
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Re: 700R4 transmission interchange

Postby Phantom » January 2nd 2011, 6:38pm

ally_g wrote:Thank you.
The speedometer driven gear I believe broke some time ago,(speedometer quit working) so the original one from the van would have to be replaced if the one in the rebuilt transmission is different.


.From what I read somewhere on this site, there was some mention of the OBD1 and OBD2 With both vehicles being manufactured before 1996 they would both fall into the OBD1 category. So, I do not understand why this other site is trying to say a lockout kit is necessary. Both transmissions are 700R4 without the electronics.I mean, both have the TV cable and the other connections. I am wondering if they are confusing something pertaining to interchanging an electronic transmission and a 700R4 that has the TV cable.

Your VIN number entered into this web link will tell you what RPO option codes your van has including what the rear axle gear ratio is , then a GM dealer or transmission shop like Jasper can tell you what speedometer gear you need to replace the broken one so that your speedo works again.

http://www.compnine.com/vid.php?vin=1gndm19w5xb126525

OBD2 came out in 96 , very very few vehicles had a full OBD2 system in 95 and those that did had a electric VSS speedo , vehicles that have the 700R4 are not OBD2
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Re: 700R4 transmission interchange

Postby Zebediah III » January 15th 2011, 6:47pm

These people at PATC in Shreveport are speedo gear gurus.
They deal with a lot of engine/trans swap customers and their shipping is fast

1-888-877-1008
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