Hi,
I have a 93 Toyota Pickup regular cab 4x4 22Re 5 speed Manual. I recently started noticing that when letting out the clutch there was
a thumping sound and the gear would then kick in. I had the clutch replaced but it didn't help. I then started hearing a terrible whining noise so
I took it in and they told me the rear diff was going out so they got a used one for me and installed that. Not too long after that I started to notice that the rear diff was
starting to leak. So I am guessing that the thump is the gear engaging and putting stress on the rear diff gears and seal. Kinda like popping the clutch. So what do you
think is the issue? The transmission or maybe the transfer case? I don't hot rod this truck by the way and I have had it since it was born so something is just
not quite right here.
Thanks for any insights!

 

I think you likely just got another marginal diff.

 

Where is the leak exactly?

Have you inspected the drive shaft joints?

You could probably isolate it as a tcase or transmission issue by dropping the rear shaft and running it in 4wd on just the front shaft.

PS, make sure the diff breather isn't plugged.

 

+1 on the leak location..
if it's coming from the flange area, the seal has failed and those bearings are surely to follow (ask me how I know) if not addressed.
It's unclear if the "thump" sound from the previous diff didn't go away with the new "old" diff.
I'm in the process of either rebuilding my diff or maybe swapping in a 3rd member from a V6 which is better for my 31" tires and 4 pinion
which is more heavy duty