For sale is an excellent Winters #8519 quick change gear set with 21 and 25 teeth.  This is set 19 and in a 4.11 ring and pinion rear end this yields a final ratio of 4.91 and in a 4.86 ring and pinion rear this yields a final ratio of 5.78.  This is a 10 spline REM gear and very nice.  Thanks for looking and as always I combine shipping when possible.