1969 THM400 transmission varients

[Dick W.]

Re: 1969 THM400 transmission varients

So far Joe all the eight bolt pump covers are for a TH 350. I am still a diggin' for an old manual that I have from 69-70. I have had one of the HD TH 400's in my shop. I stumbled over it for 3-4 years but I do not remember the front pump. It said something on the tag about being HD

[Joe L.]

Re: 1969 THM400 transmission varients

Dick-----

Actually, I think that the THM-400 front pump was either a 5 or 7 bolt cover-to-body attachment, but I wasn't sure enough about it to say so.

[Terry M.]

More 1969 THM400 transmission varients

Wasn't there a thicker case on some HD TH400 transmissions? I had heard there was.

[Joe L.]

Re: More 1969 THM400 transmission varients

Terry-----

Not that I've been able to find in any SERVICE parts information or in any other literature I've checked. The case used for all 1968-72 Corvette, as well as other 65-72 Chevrolets, was GM PART #8624966.

Thinking about it, a different case would have been a HUGELY expensive item in terms of tooling costs, etc. It's hard to imagine that such a thing would have been done for the very small number of these HD THM-400s that were ever made.

[Joe L.]

Addendum

One other thought: it's possible that both a standard and "HD" case were used in PRODUCTION while only the "HD" version available in SERVICE. I really doubt it, but it's a possibility. Unfortunately, I don't have any information on this. I'm sort of a "babe in the woods" on automatic transmission issues, anyway; I've never really studied them, at all.

It would be very interesting to have folks with THM-400s out of a car report on what casting numbers that they find on the main case. The casting numbers would certainly be different if the cases were different.

[Terry M.]

Re: Addendum

The one I heard about was in a GMC pick-up with V6. I was told it was the same thicker case used on the Corvette units. Maybe urban legend??

[Joe L.]

Re: Addendum

Terry-----

I expect so.