Decided to change differential oil , so I ordered a 8.2 differential gasket, only to find out it was to small. It was 9' center to center bolt holes, mine is 10' center. Anyway after researching I found out my differential is a 10 bolt 8.75. It has the 12 - 3/4" head bolts holding the ring gear to the carrier and 3" axle tubes. Only number marking I can find is on the back side of differential bottom, one side clock dial with hand on 2 and letter F, other side number 480632. I found they only made them in the early 70's for heavier duty applications , towing etc, parts are hard to find. Anyone know where one may find differential gasket , if not I will do the Permatex RV gasket maker.