quick question for you guys, How do you know what your gear ratio is, I looked on the engine specs and it said 3.55 boreX stroke is that what I am looking for? I have a 06' F150 Screw 4.6L Fx4

 

Look on the label on the drivers door. there is a code. Then do a search on this site for rear end codes, match it up and you got it. Also, there should be a tag on the gear pumpkin if you want to slide under and look. it will say the ratio.

 

I am sorry but where is the gear pumpkin located, I am new to all this

 

The rear axel, the middle, where the drive shaft goes in. Right in the middle between the rear wheels.

 

"06' F-150 Screw Fx4 XLT 4.6L " - now you're starting to worry me

Rear axle - the big heavy thing between the rear wheels ...

Easier to get the door code & search.

If it is indeed a 4.6 it's very likely it's 3.55 ...