Can anyone assist with putting an ID on the number from a Powerglide? I have an old transmission book but it's not helping with the identification.


T201651



THNX

Powerglides have an ID code on the verticle side of the pan. Pontiac had a two-letter code. Otherwise, part ordering is by serial number.

Light duty PG's, 1.82:1 gear ratio, have a dark (black) color 'grainy' input shaft and one less friction plate and steel plate less than heavy duty trans. These were mainly behind 6-cylinder engines and maybe low power V8's, but not likely.
Heavy duty PG's, 1.76:1 ratio, have a silver colored input shaft, as in machined surface and installed behind V8's.

But you won't be able to tell unless you pull out the sahft a ways, then you risk dropping the thrust bearing behind the shaft - you can 'fish it back into place' with the shaft. best to have the trans on its tailshaft when pulling so gravity doesn't move the thrust bearing.

Visit JC Whitney to get a manual published by ATSG, it'll help immensely. You can swap a piston from a V8 into a 6-cyl trans for the extra plate/friction disc and input shaft to get the 1.82 ratio. I did and kept redlighting at the starting line until I picked a different spot to leave.

All this info is for an alum case from '68-'73. Earlier PG'S alum case, '62-''67, have two oil pumps, front & rear, I think! - not good. And very earlier PG's, since late '40's to '61, were cast iron cases - very heavy.

Everett is correct about the front and rear pumps, and I think that this was only the cast iron case model. Maybe there were a few alloy case that had the dual pumps, but the more desirable were the later cases.

Only thing good about the dual pumps was you could start a car by pushing it , thus the rear end drove the rear pump and clutches, that would turn motor over with trans in a gear. Did a few this way.

You could also burn the back section out of a front pump only trans, as no oil was circulated at the back output shaft, if you pulled car too fast or too far.

Yes, the early alum case (62~66) were two-pump units.
The 'push-start' feature came in pretty handy for me a few times :D
You could flat tow your car with them and not risk burning up the trans.
There were some low-power/cost units used in the ChevyII and Corvair that lacked the dual pumps.