Amsoil??
 

Im goin to start running Amsoil in the front and read diffs. I am wondering if i need to flush the diffs before i can start running the new oil or what.

No need to flush, just remove the cover, let it drain for an hour or so, replace cover and refill.

I cleaned mine out with some break cleaner just to remove any sludge, but its probably not necessary.

If it looks dirty a flush can be done but should be done with the same fluid you're putting in or another gear lube. Here's the potential problem with using chemicals to flush:

Do not use solvents to flush transmissions or differentials.
Solvents can have the following negative effects on gears
and bearings in differentials and transmissions:.
• Foaming – Residual solvent such as, chlorinated
solvents or solvent-type flushing compounds
used to wash out the gearbox may cause foaming.
• Rust – Gears, bearings and internal parts if left
dry and free of oil, can start rusting in a very
short period of time after they are washed down
with solvents.
• Viscosity Loss - The presence of even a very
small amount of solvent-type flushing compound
can reduce the viscosity of oils.