I've got a line on a ring and pinion set from a 2009 f150 that I want to put in my 2012 f150. Will they fit? Please tell me they'll fit so I can ditch these 3.15's.

 

Yep. It may be cheaper to find a wrecked '09 - '12 & swap the whole rear. If it it 2wd. Is your's an 8.8 or 9.75 ring gear? You may void your warranty doing this and will need a speedo recalibration.

 

Tuners can calibrate for new gears without having to visit a dealer........ My SCT X3 will for sure.

 

Why not just buy new gears? Not THAT much more. especially in a brand new truck i see no reason to be cheap.

 

This is conflicting data with what I've found so far. What I've found so far is that in 2011 Ford went to a larger pinion bearing in the rear end.

Because new gears are only available from Ford and they are $500. These gears only have 35,000 miles on them and are a $100. That's why I'm not buying new.