Changing just the carrier isn't too bad.
If you measure from the flange where the bearing rides to the flange where the ring gear bolts on the truetrac and the stocker and compare the two you should be able to adjust the shim stock to get the proper backlash on the first try or two.
Backlash and mesh pattern have to be good or you'll have issues with the ring and pinion and premature failure.
And be sure to use loctite on the ring gear bolts when you torque them down.