I'm considering replacing my stock 3.5 rear gears with 3.73 for extra pulling power. My 2004 2wd Expedition has the 4.6 and when I pull our 3000# camper up steep hills it has to work. Has anyone done this swap? Can I find the new gears at a junk yard? If I decide to pay someone to do it about how many hours of labor would it take.

I know the real answer is I should have bought the 5.8 engine and the towing package with the steep rear gears.

 

Can I swap in gears from a F150?

 

couple things. you can get new 3.73's fopr just over $100. as far as used ones, they interchange as longs as they come from the same size rear housing. being that you have a 2wd, i assumeyou have the 8.8, and not the 9.75. you can use 3.73's out of any 8.8 rear diff, but again, you are better off new. also, you will need the dealer to flash the pcm for the new gears or your speedo will be off and shift points may be weird. and yes, for towing the 5.4L with tow package would have been a better choice. keep in mind, you have the 4r70 or 4r75w, so i highly recommend adding a trans cooler.

 

Thanks for the help!