This past weekend I replaced my rear transmission seal and it is still leaking just a bad as it was before. I have done this job before on my previous truck with no problem. Am I missing something or could I have gotten a bad seal. One thing I did do different is rub some tranny fluid around the outside of the seal so it would go in easier. I would appreciated any help. Thanks!

 

What condition is the yoke in where the seal rubs on it (is it pitted or scored..?)..?

 

The yoke is in good shape. All I did was replace the seal drive around the block and park, maybe one mile. And it is still leaking

 

What kind of transmission and what vehicle. You say you did it in your OTHER truck, which leads me to believe it's a truck.

So when you put the yoke in can you move it around like the bushing is worn?
Does it have a bolt on yoke? If so did you put sealer on the splines?
Depending on type of trans and yoke did you check the inner o-ring?
Does it have a vented yoke?
Did you check to see if the trans vent is clear?

Heres an o-ring housing on a 4L80E, it uses a vented yoke. Some other transmissions have them, some don't. older 4L60E's, 700's, th350's while th400's have a o-ring on the output shaft whether slip yoke or bolt on, 4L80E's too with bolt on yokes.

 

The transmission is a 4L60e in a 93 GMC truck which I figured would be the same as my 02 WS6. Would a wore out bushing cause the rear seal to continue to leak even if the truck is parked. The yoke is just attached to the drive shaft via u joint, I am not sure about the vented part or how that pertains to the tailshaft, yoke, or it leaking.

 

The picture I posted above has a sleeve with an o-ring on the inner diameter. This is used with a vented yoke, thats a yoke with a small hole in the end. If that o-ring wears out, fluid will leak out of the hole in the yoke. You can change the seal 100 times and it'll still leak if the o-ring is worn out.

It could be a nick in the tail housing bore where the seal goes, I use loctite around the OD of the seal to prevent leaks.

You need to find the problem, if you pull the old seal out and don't see anything wrong keep looking.