So after using the infamous zerosearch feature... I found out it could be a couple of sources... but first a background of my problem...

Just swapped motors. Same D16Y8 as my car came with, just built up.
Axles came out.
Left axle clunking slightly.
Trans fluid leaking out of tranny, right side I think.
Replaced both drain and fill bolt crush washers.

From what I've been reading, it could be the axle seals. If so, is it hard to replace? Nothing more than dropping that axle out again and removing the seal w/ my fingers, correct?

Kinda off-topic... but the clunking axle... the axle has a snap-ring on the trans side... Helms says to replace it after every time ya remove the axle. The axle's been out twice now. Perhaps it's because of the worn-out snap-ring (it functions to tell you if the axle's in properly, and maybe to hold it in place too?) that's causing the clunk?

 

You might have over filled the transmission.. mine was leaking and i was pissed.. then realized it was over filled .. Does it clunk all the time or only when your slowing down or staying at a constant speed.. if its the latter of the 2 then you have a bad cv joint and need to replace the axle. Hope this helps!

 

Well as it turns out... it's a little bit of everything... put the car up in the air today...

After putting in the new engine, we got a little overzealous and thought the left axle/halfshaft was installed properly. It was instead just set inside the tranny and not pushed into place. Therefore, the trans fluid is leaking out of the left side of the tranny where it meets up w/ the axle... cuz they're not in place! This would explain both the leaking fluid and clunking!

Thanks for the help... I wish I had looked more carefully first!