i went from the strock tires (tiny) to huge 285/75/16 tires and i pull a trailer im wondering how much it would cost to convert the gears. and should i move to a larger gear than the 4:10 if so what are my options

 

You're probably looking at around $500. per axle. I have a 4x4 so it was double the cost. I wouldn't go any lower than 4:10 unless you're going to pull something heavy and often. 4:10's will give you better accelleration without burning too much gas. You should pick up about 400 rpms.

https://www.f150online.com/galleries....cfm?gnum=7238

 

I'd go for the 4.56 for a 4.6L.

 

and that would cost around 1,000? how much would it cost if i could get the parts ? i have a friend who says he can do it

 

I've read $1500 for parts and labor. Parts, less than half that. Rear is easy, but the front/transfer case isn't fun.

 

you have to do both of them"?

 

Not if you don't ever engage 4wd or you want to replace your tranny and transfer case the first time you use 4wd. Yes, 4wd means both axles need to be replaced.