I'm looking at swapping out my 3.31s for 3.73s. My truck has the 9.75" rear diff. I found some used gears and they're listed as being for a 9.75" diff, but from a F250/F350. Will these gears fit my F150 9.75" diff or are the 9.75"s in the F250s and F350s different? The Ford part number of the gears I'm looking at is 5L3Z-4209-F if that helps. Thanks.

 

Not sure. I would think they are the same. You could call a Ford dealer and ask the parts guy maybe if no one responds.