noticed the th400 I used in my chevelle originally came out of a 66 impala. I know if uses a different filter, But after comparing the yokes. The 66 one uses a OD yoke vs. a 70 th400 I have sitting here. So is there other differences? thanks jim

tail-shaft on trucks and big cars (IMP'S) is usually longer, making the x-member mount back further and a shorter driveshaft :)

These are both short tail turbo 400s. Its just that the one out of the 66 has the same spline count as the 70 turbo 400, its just the OD of the yoke is smaller. Fortunately when I parted the car out. I kept the yoke, which I believe was a 1330 yoke. Ive got a th 400 from a 65 impala in my 71 camaro. On that one too, I got it with the original yoke. Or I may have had a hard time when I did the swap. jim

my t400 came from a 69-caprice - had long tail-shaft.

noticed the th400 I used in my chevelle originally came out of a 66 impala. I know if uses a different filter, But after comparing the yokes. The 66 one uses a OD yoke vs. a 70 th400 I have sitting here. So is there other differences? thanks jim

What is an OD yoke?

After rereading what I wrote I guess it should have read "the yoke on the '66 tranny has a smaller outside diameter than the 70 yoke." I just thought all the short tail th400's used the same yoke. jim

Different filter??

Hello, i think what he means as to a different filter is that the older th400's had a long narrow telescope lookin filter and the newer ones had the flat pancake style. the older filters are still availible but are getting pricier.

Thank you Craig. All I have ever seen is the flat style.

Here's the OD of the yoke
the later yoke for the 70 is 1.875"
the earlier yoke for the '66 is 1.686"
This is with the el cheapo caliper. Jim

Hello, i think what he means as to a different filter is that the older th400's had a long narrow telescope lookin filter and the newer ones had the flat pancake style. The older filters are still availible but are getting pricier.

The earlier TH400's had a depression on the bottom of the pan that looks like the imprint of the heel of a man's shoe. The change to the flat filter was around the middle of 67 as I recall.

Here's the OD of the yoke
the later yoke for the 70 is 1.875"
the earlier yoke for the '66 is 1.686"
This is with the el cheapo caliper. Jim
Different outside diameters with the same spline count is news to me--but--makes sense as an answer to someone on a Pontiac forum that is battling the same problem.

I do know that there are vented and non-vented yokes; the vented yokes need an O-ring on the output shaft to prevent fluid leakage.

Early TH400's had a smaller outside diameter yoke. Thin wall yoke, later models all got the "truck" diameter yoke.

I just posted it because I found it interesting. jim

The vented yoke is used on the th-475 and is a strictly bolt on deal. The "vent" is where the bolt passes through the yoke to the trans tailshaft. The vented yoke, like was stated, is sealed with an "O" ring and is machined internally about 1" deep. The "o" ring seal can only be used with the vented yoke in the stationary position.

A special yoke is required to use a slip yoke on a th-475.
Although I don't know of anyone who has done this, but I'm convinced that the th-475 vented yoke can be used as a slip yoke on the th-475 trans if the "vent" is sealed and the driveshaft if the proper length. The only reason I would see to do this is if you already have the vented yoke. You will need a different driveshaft anyways if you are replacing a Powerglide or a th-350..

Driveline shops are the ones that sell the "special" yoke, so it is not in their best interest to reuse the th-475 yoke.
Squido