That is a bend over and take it price, local shop here is $100, and he gave me a gallon of gear lube.
I have yet to put the 4.30 gears in my Duster to replace the 3.23.
He also told me the best way to break in gears, is to run it easy down the road for at least 15 minutes to warm the rear end up.
Park it over night repeat 2 more times. Basically heat cycle the gears to set the wear pattern.