Hello, What is the bolt patter of my truck?

I want to install new wheels, and this are my options:

6X135 (bolt pattern) 4.5" backspacing

or

6X5.5 (bolt pattern) 4.5"backspacing

any recommendation?

F-150
1999
4X4
5.4L
3" PA Lift Kit

 

Um, doesnt the 99 have 5x135 ? my 98 did

 

Correct, your truck has a 5x135mm bolt pattern and the OEM wheels have 4 1/2 inches of backspacing, which is what you need on aftermarket wheels.

 

Ok the wheels must be
5x135 4.5"

now, wht about the 8.5 " vs the 10", what of those would look better for 35" wheels?

 

That's a matter of personal opinion. I think 10's look better.