Yeah it is tempting to go after a Ford ranger 8.8 due to the ease of the swap. I'm going to see if they can be found in other gear ratios. On another note, it looks like the 05-13 mustangs have 8.8 31 spline axles. It looks like the axle width (wms) to wms is about 66in though I can't find anything on the pinion offset distance.
