i suppose it's fairly common knowledge here that the hummer [h1] has amc20 differentials, and also that they carry what is imho the best posi ever, the gleason torsen. it does not work through friction and needs no special lube; instead, worm gears on the carrier drive the side gears. it doesn't 'wear out' like conventional posis. until now, i had thought that because of the axle-hub gear reducers they used only tall gears on the 2-series case, but according to this http://www.vibratesoftware.com/html_help/html/HUMMER/Hummer.htm they also offered 3.08 gears. this might have a thick ring gear that goes on a 2-series diff, but it could also mean they have a 3-series amc20 case too! jeeps had a 3.07 that went on the 3-series case. i don't know of any other 3.07/3.08 for an amc20 2-series, which would make the hummer gears unique if they are. btw if this doesn't sound high performance, indycars also run torsen diffs - exclusively. ________________________________________________________________________ Andrew Hay the genius nature internet rambler is to see what all have seen adh@xxxxxxxxxxxxxxxxx and think what none thought