I searched this already and i am even using a chart i found on ps.com, http://www.pavementsucks.com/forums/viewtopic.php?topic=56143 the numbers on my ring gear dont make any sense or match up with the chart. my truck is a 87 w/ a 305, 700r4, 208 stock ten bolt f+r.. so what is my gear combo? the number i found on my ring gear is 255 12 41 3.