My 2000 450es made a pop noise and now the rear wheels will not pull does anyone know what happen?

 

Two things come to mind.
#1. You stripped all the splines off of the hub.
#2. You stripped all the teeth off of the ring gear.
Bad news either way. :-(
Oh, 3 things; you stripped all the splines off of the imput shaft.

 

check the u-joint inside the rubber boot