That's how I was taught to do it too. If you have 3.73s, the driveshaft will turn three complete revolutions and 3/4 of another revolution. If you have 3.55s, the driveshaft will turn three full revolutions and slightly more than 1/2 of a revolution.
The easiest way to make sure you turn the wheel exactly one revolution is to put the valve stem at the 12:00 position, then mark the driveshaft and a point to reference it to on the diff case. Then, when the valve stem goes around to the 12:00 position, you're done.
One other thing: IF you don't have posi, both wheels will have to be turned by two people at the exact same speed. Otherwise your results will be false.
or you could just turn the driveshaft
03 PI 4.6, 2 row Fluidyne radiator, CAI, 90mm MAF, 24lb fuel injectors, 75mm TB/Plenum (P&P), o/r hpipe, Magnaflow mufflers, Steeda timing adjuster, 12lb alluminum flywheel, King Cobra clutch, Short throw handle, 3.73 gears, Eibach springs