changed the dope in my diff. this weekend,usually just loosen the bolts let it drain and retorque and fill,decided with almost 400,000 mi to pull the cover and look inside. first checked with advance to see if they had a gasket just in case,they didnt stock it but could get it for 55. 00 dollars. gears looked good old gasket looked good 55 dollars not spent. still cant believe that gasket is 55 bucks.