Hi guys! I'm sorry if this seems like a very simple question but I want to make sure that I'm doing this correctly and don't mess anything up. Can someone please explain how to replace the rear tail seal on a TH 350 on a 72 cutlass supreme 350. I hope I'm calling it the right thing. It's the seal right before the driveshaft. Thanks guys

 

You just need to pry the old one out and carefully tap the new one in.

 

Eric, it's that easy???

 

Pretty much that easy. I like to use a thin coat of silicone on the edge of the seal
just for piece of mind.

 

So you jack up the back of the car and don't need to drain any trans fluid?

 

When you pull the prop shaft, you will want a pan to catch the fluid that will come out.

 

Thanks Gary and Tru-Blu. I don't have any fluid in it yet since I reinstalled the trans. When reinstalling the seal what's the best way to tap it in To make sure it seats properly? Should I use a socket that's about the same size?
​​​​​​​Thanks!

 

A socket or a piece of pipe.

 

That would have been the best time to access and replace the tail shaft seal. You might also want to consider changing the o ring for the driven gear sleeve while you're at it. It also is prone to failure and leaking.

 

Be sure to lube the seal lip or lube the driveshaft yoke before you drive the car. Seals should never be left dry. They will burn up and leak.

 

^^^This.

The preferred lube for automatic transmission seals is petroleum jelly. It sticks to the seal and will dissolve in the ATF.