Where do you find....

[Montezuma]

the numbers on the differental that indicates what variation it is.

[Mr Camouflage]

Casting numbers are on the top of the diff. If its in the car, you'll need a mirror.

If you want to know the ratio, you'll have to open it up, as its stamped on the crown wheel.

[beandip]

the numbers on the differential that indicates what variation it is.

For one thing the R-200 is larger than the R-180 . The two studs on the rear of the diff are larger on the R-200 . The numbers are stamped on the ring gear but you would need to remove the rear cover . What are they out of ? If you know what Z the diffs. are from, then we can tell you what they are, and the gear ratio. Automatics have 3.54 to one and manuals 3.36 to 1 MOSTLY . Some 2 + 2s have the R-200 with 3.70s . Zs with 5 speed tyranny's have 3.90s . so you see it helps to know what the Z was that they were pulled from . Gary

[ktm]

The stamps on the ring gear will be two numbers offset by a colon, such as 39:11 (3.545) or 37:11 (3.36).