I have an 02 auto with only a densecharger, and I'm thinking about going with tlok and gears next. I know people say manuals should go 3.73 and autos should go with 4.10 but I wasn't sure if I could handle the change in mpg. I was looking at http://www.stangparts.com/home.cfm?section=products/index go to "rear suspension" and then page 4 and they have used tlok and 3.73 gears. At gefracing, a new tlok costs just as much as both of the used ones, so I was wondering if there is a big risk by buying a used tlok and gears. In the link, would the tlok work with the gears? For the tlok it says "8.8, 28 spline, STOCK, traction lok" and for the gears it says "Ford, 7.5, 3.73, includes ring gear, pinion & pinion nut. This is a used unit." Does it matter that one is for the 8.8 rearend and the other is for 7.5? I'm just trying to make sure that if I get both I would have everything needed for the mechanic to install it. If there is something else I'm missing, I'd appreciate any advice.