Can't offer much input on the diff--I think if anything my rear would be the first to go. What is max speed on an '03 Bean? I've always been curious where they're governed. I heard 124 but don't know how accurate it is.Just shy 200,000 miles so some things are bound to happen, with plenty of full-throttle romps and the occasional run up to max speed taken into account...
The noise isn't that bad now, but it is progressing.
Front diff fluid has always looked and smelled fine, has even been changed on occasion.
There's no such thing as magic goo in a bottle, but sometimes the right stuff can stretch it out.
That's because your LL Bean uses the MPC and is predominately FWD.Noise with rear wheels on the ground and not moving:
Bad front pinion - YouTube
I think this is definitive, front pinion bearing.
I also confirmed even in 1, there is NO drive to the rear wheels until you step on the gas (whern I had all 4 off the ground, heh)