gear oil
Big 17mm bolt basically straight back from where the axle goes into the transmisison on the passenger side. Easiest to get at from below, make sure the car is level when you check it, the level should be flush with the hole.
Jack it up, pull the drain out, put it down and let it drain, at the same time take the fill bolt out, then jack it back up and put the drain bolt back in. Then from above you're going to need a funnel with a hose, stick the hose in the fill with the car on the ground and pour 2 quarts in, then you should be able to put the fill bolt back in from above.
I unbolted the top bolt first with the car level, then removed the bottom bolt and let it drain, then put the drain bolt back in and filled it up through the filler bolt. It's pretty much just like changing oil. I recommend using the Pennzoil Synchromesh. It's designed for Chyrslers and GMs because their transmissions are made of yellow metals, like the H22 tranny.


