I just changed my stock '95 long as*ed 2.73 rear-end over to a complete rotor to rotor LS1 rear with 3.42's. Everything went OK as all the parts lined up.

Now the only problem I have is the increadible noise from the rear! I dumped the goo out of the LS1 dif. and filled it with Mobil 1 synth. (I already know this was a mistake ) I later added the GM additive hoping to see SOME improvement before switching to castrol and GM additive. Still lots of deafening noise at highway speeds.

My questions are:

A: Did I screw this up by running Mobil synthetic?

B: Should the rear make the rumbling/slushing noise when using synthetics?

C: Other than clutches/cones slipping with sythetic, will the swap to dinosaur oil really change the volume and expensive noises coming from the rear end?

D: Have I hosed myself with the rear end swap?

Thanks in advance for any help or advice.
Craig