700R4 different types?

[chromeblvd]

Hey gang! Very new here.  I've read a lot of posts (including the 700R4 site...which led me here... )but haven't been able to find the correct answer. :?   My pull vehicle is an 89 chevy suburban 4x4 with a 350 engine and turbo 350 transmission sitting on 35" tires.  I'm in need of a transmission rebuild... should I just rebuild what is there or upgrade to a 700R4 (getting an overdrive)?  Currently, at its best the truck gets 11.5 mpg.  Obtaining an OD may help toward fuel costs.  In my search I came across this link http://www.fearthemonster.com/transmissions/monsterminion/stock/700r4/ which shows two different types of 700R4 transmissions.  My brother has a 700R4 on the shelf.  He planned on using it a while back but changed his mind.  I haven't seen it and the cost is just right.  Until the link above, we didn't know there were two types of 700R4's.  Can anyone tell me the crucial difference between them?  Besides the obvious-one is for two wheel and the other is for four wheel drive applications.  ie... difference in gearing, bolting to engine, shortening/lengthing of the driveshaft??? It appears by the photo that the four wheel drive is shorter.  But are these photos accurate?  Without having the two side-by-side, we don't know which one we have.  Will either one work?  Just trying to eliminate additional work.  Any help on this matter will be greatly arreciated.  Thank you!

[phat rat]

Based on my experience with a 94 Burb 350 w/od you won't spend much time in OD with 35" tires. What gear do you have? Mine had 3.73 and when I went from a 245/75x16 to a 265/75x16 my mileage dropped a bunch and I spent more time out of OD ,  plus towing in OD isn't recommended. Went back to 245's and mileage went back up and so did the time spent in OD

[Fat Cat]

I am sure Crosley will be along shortly.

But I can add that there is a difference between a 2 wheel drive and a 4 wheel drive 700R4. The output shaft on the 4 wheel drive version is shorter due to the attachment of the transfer case and adapter right directly to the trans

[chromeblvd]

My pull vehicle is an 89 chevy suburban 4x4 with a 350 engine and turbo 350 transmission sitting on 35" tires.

Correction... it has a TH400 not a TH350 as one guy had pointed out for me.  I just got done comparing and it's a TH400.  It only has problems in cold weather.  The truck needs to warm up before engaging into drive or reverse. Is there a particular reason for this??  Is this a repair job for the DIY??  Or should I just take it to the tranny shop and be done with it?

[Crosley.In.AZ]

there are 2 different bell housings for a 700/4L60 tranny.... a V-8 chevy bolt pattern and the smaller V-6 bolt patterns.

You need to count the splines on the input shaft of your trans.... it will be the shaft that 'spins' NOT the fixed shaft.  27 splines is an early trans (pre-january -1985), 30 splines is later.

You can not unbolt the t-350 and bolt in the 700/4L60 trans and drive away.  Different length trans, different adapter needed for transfer case, drive shafts will be different lengths. TV cable VERY important on the 700/4L60 trans.

This page-clik here  may help you ID a tranny manufacture year.

..... 4L60 and 700r4 are same trans , different name by GM

[Crosley.In.AZ]

My pull vehicle is an 89 chevy suburban 4x4 with a 350 engine and turbo 350 transmission sitting on 35" tires.

Correction... it has a TH400 not a TH350 as one guy had pointed out for me.  I just got done comparing and it's a TH400.  It only has problems in cold weather.  The truck needs to warm up before engaging into drive or reverse. Is there a particular reason for this??  Is this a repair job for the DIY??  Or should I just take it to the tranny shop and be done with it?

a whole different situation. You will need to change the transfer case too if you want a 700 tranny in there.

T-400 has a larger diameter output shaft  , so the t-case has a different setup / adapter.

Sounds like the t-400 has morning sickness.... aka hard internal seals . When cold the seals  do not hold pressure till some warmth gets in there.

The tranny could need a full over haul.

have fun.

[chromeblvd]

Sounds like the t-400 has morning sickness.... aka hard internal seals . When cold the seals  do not hold pressure till some warmth gets in there.

The tranny could need a full over haul.

have fun.[/quote]

Thanks Guys!!! I will dig deeper in my pockets to get the tranny rebuilt.  Just ordered a new engine this morning... haha, when it rains it pours... :(D) ouch!