I going to ask a question that I'm sure everyone except me knows, so be nice. I need to change gear oil in the rear end. I don't see a drain plug. So I assume that the cover must be removed from the the rear end. My question is this: does the cover need a gasket or do you just use silicon gasket material? My truck is a early 1999, F250 4X4. /ubbthreads/images/graemlins/shrug.gif Thanks