Need to know what transmission fluid to put into it and many more questions your the only person in 3 days searching who knows anything about these vehicles
Quote Originally Posted by Robyn View Post
I had an 82 K5 (Jimmy) with a 6.2 and the 700R

The tranny gave up and literally scattered all over the street in a splash of oil and broken parts.

The 700R was very expensive to rebuild then and finding a good core was tough too (at an affordable price)

I used a spacer and a slightly longer tail shaft (all came in a kit) and replaced the 700R with a TH350.

Truck got about the same mileage as it did with the 700R too.
Truck was equipped with 3.42 gears and I had oversized the tires some too, so the change in trannies was not a big deal.

The TH350 IMHO is a far better tranny that the 700 ever thought of being.

A 350 with just a shift kit added will outlive a 700R and take just about anything you can toss at it.

One box thats not talked about often is the TH350 C, these had a lockup converter, but were otherwise just like any other 350.

With the lockup conveter most of the mileage loss is gained back, unless you are running low butt gears.


My K5 always got about 20-24 MPG and it did about the same with the 350 as it did with the 700.

I sold that truck to a local fellow and he had a 700R put back in the truck and it died within a year, so they put the 350 that I sold it with back in.

As far as I know that same 350 is still in the truck today and this all took place in the late 80's.

Best tranny bar none for holding up and not needing any fooling around is the old TH400.

A 400 with a shift kit and cooler can take just about anything you can throw at it and shrug it off.

Now if we start talking DMax level power, then the Allison comes into view.

The only issue with the 400 or the 350 is that when used with the diesel engine, there is a need for some sort of vacuum and controls to handle the needs of the TV circuit.

The factory used a vacuum switch mounted to the IP that sent controlled vacuum to the modulator to maintain the correct TV pressure.

This system worked quite well actually.

Adjustments were either done by the seat of the pants or by a gauge setup.

I always used a pressure gauge and the old Butt dyno.

As long as the vacuum was not too low at moderate to heavy throttle, you were fine and the tranny was happy.

The reason for the 6.2 was really all about keeping the CAFE (corporate average fuel economy) numbers up and the 6.2 coupled with the 700R did a fabulous job at this.

Even a 2500 Burb 4x4 with 4.10 gears could (when new) pull down 20 MPG ++ out on the highway.

This was using a TH400 and not the OD trannies.

The 350 was pretty much phased out when the 700R came on the scene.
The 700 was used in almost all the rear wheel drive cars and 1/2 trucks and the S10 too.

The big difference was what they installed in the box in the way of clutches and the VB settings.

The cars and such got a very light duty 700 and the 1/2 ton pickups and Burbs got a heavier duty one. (dont confuse this with REAL HD)

Now, the truth is, the 700R as it hit the streets was an abortion, with more problems than anyone needed.

It was not until about 1987 after amny many changes and upgrades and the aftermarket folks had really dug in and got traction that the 700 finally became fairly reliable.

To some it up, the TH 350 will do an admirable job behind a 6.2


Just some thoughts.


Missy