I agree with the group here, but I upgraded my 7.5 to 3.73's and t-lok. I chose Ford Racing gears and had them installed at Pro Dyno. That was over 40,000 miles ago and she's still holding up fine. And I don't exactly baby the car and have taken it to the track for a few runs. But you might as well go for the 8.8 if you have the opportunity.
ProCharger Stage II - Pro Dyno tuned - Visit my garage for complete list of mods