Set 20 is a 20 tooth gear and a 26 tooth gear. From the Winters page
http://www.wintersperformance.com/ca.../index1024.htm On page 18 there is a chart
if you put the 20 on the bottom, you will have a 3.17
if you put the 20 on the top you will have a 5.36

These are from the 10 spline 4.12 ring and pinion chart.
If you have six spline gears, look at the other chart.

Mike in Tucson