if I turn my driveshaft one complete revolution, and my tire turns about 11/2 turns, whats my gearing ?
the proper way is lift one tire off the ground. spin the tire 2 times around, and count the driveshaft revolutions. very easy, very accurate. put marks with chaulk or anything, i've often used just spit to mark it. gm commonly used 3.08, 3.42, 3.73, 4.10, 4.56. . if you know how fractions work you can judge what gears you have by how the marks end up.
when i go buy a set of axles, this is what i do and i'd bet any amount of money i know what's inside.