Please Help Me Identify What I Have

easy way to check-rotate input counting how many revs it takes to get the output to rotate once. like for an overdrive-in 1st gear rotate input 3.09 times for 1 rev of output. in 2nd 1.67 revs of input for 1 of output. in 3rd 1 to 1. in 4th .7 revs of input = 1 rev of output