I installed a Eaton TruTrac in my 8" rear with 28 spline axles and 3.25 gears. The engine makes 315 at the crank; 260 at the rear wheels. Eaton tech told me the 8" with this diff would be good for up to 350hp at rear wheels no problem. The TruTrac is a Torsen unit where there is always power to both wheels, which actually is a handful in the rain such as a slick off-ramp because there is no "clutching" and operates more like a straight-up locker (although they are turning at different rates). You can really slide the car around and apply predictable power when roads are slick, but you have to be on your game on the street. I went with this diff because I wish to track the car this year (installing the multipoint cage now) and a previous 8" limited-slip diff didn't perform well at all. Look up Torsen diff and you'll get the idea of this parallel helical gearing. The unit was around $700 and I did the install with a dial indicator, a good workbench, oven for heating ring gear, etc.