99' Pathfinder noise in r/rear maybe?

[livegood]

Hey guys,

I'm new to this forum and I have been enjoying my 99' pathfinder. I have done much maintenance such as major tune, timing belt/water pump/t'stat, trans service, rear axle fluid etc. More recently I have noticed a noise. It sounds just like what a engine crankshaft thrust bearing sounds like (low rapid knocking or thud) when under slight load or on initial take off from dead stop. Lasts about 2 seconds, but very noticeable. This is not however, an engine noise, it's coming from somewhere in the rear drive line/axle area possibly. The noise is only in drive on take off and in right rear; no noise once rolling. I can hear it every time. Tried taking off gently in drive with parking brake on; no noise. Took off brake, heard noise. Doesn't make the noise in reverse. It's like tap tap tap then that's it. Just enough to bug me. I haven't done any further inspection
This is a 2wd, automatic, 144,000 miles. Mechanically otherwise in fantastic shape. My only thought right now is that possibly, somehow this one might have limited slip diff, but don't really know, and may need better fluid and or additive. I mention this because I did pay a shop in town to drain and replace the rear axle fluid a couple weeks ago. I don't usually let others do this but maybe they used some generic multi-purpose type fluid?
Any whooo, if any one can offer suggestions, many thanks to ya.
... Oh, before I forget, also have funky rattle sound in rear body when run over even slight bumps in road, almost like loose panel or something similar,
Thanks, Bill

[smj999smj]

For the driveline noise, I would check the driveshaft U-joints and engine/trans mounts. For the other noise, check the exhaust system and heat shields.

[livegood]

Thanks smj999smj...
u-joints can make that type noise; I'll check it and let you know,
Bill

[livegood]

OK,
Just jacked it up and checked all the joints, shocks, hangers, shields, pans, brackets, you name it. This one is pretty tight and clean; looks new under there. I also drove again; no noise since sat a few hours, go figure!
I'll check more later after driving awhile. Doesn't appear to have LSP though. I am an old mechanic but I don't think I'm paranoid yet,
Bill