Re: 4.6 swap to a 5.4
As for the rear end gears for the GT500, I should have been more specific. I think the 2007,8,9 all came stock with 3.31 gears. I think the 2010 and up have a different gear 3.55 or 3.73's.
For other Mustangs, ie Mustang GT, my '06 came with 3.55's, but I have seen other size gears that also came stock in some for the same time period.
2008 GT500 Coupe with a few mods here and there