I have 33x13.50x18s on my truck and I may eventually go 35s. So what gears should I go with 3.73s 4.10s etc? Also what size rear end is on my truck, I think it is a 9"? What is the stock ratio?

 

it all depends on your setup. Its a 9.75 rear end, but the gears in it now may vary. you could have 3.55 or 3.73. Your tag on the cover should say. IMO, you wouldnt have any problems turnin 35s with 3.73s, but if you want your power back and everything basically back to normal, you may want to upgrade to 4.10s(if your going to tear into it you may as well do it right). Only thing you gotta remember is if you go bigger in the back, your going to need to go bigger in the front. And changing gears can be a stressful job for a shadetree mechanic. I had never done anything with gears in the rear diff, and i just changed all bearings back there a couple months back, and it was fairly easy fix, but specs for gears are very critical. but anyway, i would go with 4.10s.

 

So I have to change out the front gears too? I dont ever have to use my 4x4 very often

 

yeh, you say you don't use 4x4 very often so 4.10's should suffice....but 4.56's would be better. and you have to change both sets of gears.

 

Check your door data sticker to see which gears you have: AXLE CODE
H9 — 3.55 limited slip (F-150, F-250)
B6 — 3.73 limited slip (F-150, F-250)

 

my dad has a shop that does nothing but standard transmissions and differentials. he's been there for about 25 years now. he recommends a 4.10 with the 33's and 4.56 with the 35's. if you EVER use the 4x4 you will need to change both sets of gears. even if its engaged on accident it WILL tear up expensive parts. (axles, transfer case)