I will soon be putting a 6" lift and 35" mud grapplers on my 07' FX4. What I need to know is if I keep the stock 3.73 gears in it will it cause any problems.
Also if I do decide to get new gears what is a fair price for parts and labor.

 

I ran 35's on my 3.73's and i think it was fine

 

3.73s are fine with 35s. If you dont already have a tuner or a cold air intake you could add those to make up some of the power loss. I had those on with my 35s and was perfect. But if you plan on going bigger than re gear. Re gearing could run from 1600-2000 parts/install

 

i ran 3.73 with my 35's for about a year with no problems

just made the switch to 38's and went with 4.88's

if you have the cash i would def regear, night and day difference in acceleration and no gear searching on hills. Its alot more "fun" to drive.

for 35's i would go with 4.88's , cost me $1,700 for yukon 4.88's installed on my truck 05 4x4, it ll prolly be cheaper since you are in Texas though , labor rates in NJ are crazy

 

You should be fine, unless you do a lot of heavy towing/hauling.

 

Thanks everyone I think I will stick with the 3.73's and mabey get an edge chip if I can talk the wife into that part. I already got the hard part done talking her into the lift and tires.