Plow Truck.... Rebuild Auto Trans?

Hiya folks

Rebuild Automatic Transmission? Or replace, or other options?

I have a 1976 Chevy 4X4 Truck (C-10) that I use as a plow truck. Short bed.

350 c.i. 350 turbo automatic trans.

Full time 4x4. In other words, it does not have manually locking hubs (yep, they made them back in ’76).

It’s a plow truck only, never hits the pavement, it gets used hard. The transmission takes about a half hour to warm up before it will work (move the truck).

I have rebuilt the transfer case before, but I have never messed with a transmission. Frankly, I’m to busy to mess with it. I’m putting an addition on my house this year, and this would be biting off more than I can chew.

As much as I hate it, I plan on having someone else do the work.

So, the question is, are there adjusments that can be done to automatic trans?

Should I go for a rebuilt?

Should I go for a new one? (doubt they make them anymore)

I would either:

[li] look for a replacement in the junkyard[/li]or
have it rebuilt

If you’ve never been into a GM automatic transmission before, bite the bullet and get either a remanufactured unit, or have yours rebuilt.

The THM 350 is one of the most common trannies out there. It was used in one form or another in nearly every GM product- car or truck- from the mid sixties’ to the late eighties or early ninties.

There’s millions of them out there, junkyards will have them dirt-cheap.

However, not all will bolt directly to your NP203 transfer case without a little work, so the best thing to do is take yours out and have it rebuilt.

A half hour before it starts working???

Sounds like something in the valve body is stuck. A rebuild is probably in order. If you were to install a “shift kit” you might get lucky an correct the problem. Even if you do the rebuild later (could have smoked the clutches by running the trans in its current condition) the parts in the shift kit can be reused.

Thanks for your responses,

Doc, you know your Chevy’s it is a np203, 157 needle bearings in that mother if I remember right. What a mess.

I think I’m going to have a rebuild done on the existing trans. I have a place that I think I trust, but I need to talk to some folks.

Anyways, a funny story for your help.

Back in 1980 I rebuilt the transfer case, in a dorm room. Got it off the truck, up the elevator to the fifth floor and into my room.
Cracked the case. … Fire alarm rang…
We all went out side…
Came back to 4 quarts of 90w all over the floor and (my) carpet.

I’m bet that room has never been the same.

“What is that smell?”




NinetyWt does NOT stink.

BTW re: the differences in housings:

Sweety and his brother rebuilt a Chevy transmission for their 2-ton farm truck last weekend.

As Doc mentioned, not all of them have the same bolt pattern. He was able to take the “good” guts and put them back in the old housing so’s they’d bolt up. (AFTER he had put it together one time and discovered that the replacement tranny didn’t match).