I have a 4.0L Fx4 that has a bent rear axle (not the axle itself but the housing). I am thinking of changing out the gears in the bell from what is there to another truck (the old truck has 3.73 gears, the FX4 has LS 4.10) Do I need to change the pinion as well or is that handled by the spider gears?

So let me clarify. I have a 2004 FX4 with a bent axle housing. I have a 2001 XLT that has 3.73 Gears with a straight housing. I want to change out the housings and drop in the 4.10 into '01 housing but need to know if I have to have the pinion. Parts for it at the junkyard to pull a new axle w/o brakes and new poarts are about the same cost. but I have them here at the house.

Thanks in advance!