Drivetrain noise, can't track it down

[ceniack]

1997 240sx auto.

I get a rythmic wum wum wum (best way to describe it) noise coming from what sounds like the drivetrain (behind the transmission). It does it at speeds greater than 25 and only under load (accelleration). The noise speeds up as my car speeds up.

I had a leaky driver side shock so i replaced the rear shocks which didn't solve the problem.

I swapped out the carrier bearing and dropped the diff (was going to change it out with a spare I had) when i dropped the diff I saw this:

http://img130.imageshack.us/img130/5236/photojh.jpg

with axle grease all in the cavity on the output shaft on the driver side. I assumed that it was the problem and swapped the axle out as well and put the old diff back in.

went for a drive and still have the same problem and am at a loss. The only think I can think of is the diff as i would think if it was the wheel bearing or bad tires (possibly from the bad shock causing it to wear funny) that it would happen regardless as to if ti was accelerating or decelerating

Any suggestions?

[[email protected]]

can you give us a better explanation or a video?

it's hard to troubleshoot through words.

[mad-ass]

that axle needs to be replaced, seems like someone went off road in high speed/deep drop and the bearings inside the axle punctured the cover.

and if the noise gets louder with acceleration under load, it may be your differential. change the fluid and see if that helps any. what diff do you have? open/vlsd/clutch type after market/welded?

[ceniack]

yeah, i already replaced the axle. The diff that is in it is the stock open diff. I am going to put the old open diff from my s13 in it.