For sale is an excellent Winters #8513 quick change gear set with 20 and 25 teeth.  This is set 13 and in a 4.11 ring and pinion rear end this yields a final ratio of 5.15 and in a 4.86 ring and pinion rear this yields a final ratio of 6.07.  This is a 10 spline REM gear and very nice.  Thanks for looking and as always I combine shipping when possible.