Pinion shaft is 1 5/8", ring gear diameter is 9 3/4", axle spline count comes in 16, 23. 30, 32, 33 and 35 with 40 available aftermarket. While I agree the Dana is a heavy ****, IMO you'd be hard pressed to see it make a big difference, since most of the time most people will be running a numerically higher gear set anyway, which will give extra leverage to get the thing rolling. Plus, people who switch to the Dana probably have plenty enough power to spare, since that's the whole reason for the switch anyway.