Be sure to check the lube levels in the differentials on new truck deliveries. I asked the dealer to double check the level of fluids in the differentials on my new GMC DM before picking it up. I had read in the forum that some trucks were coming through with low fluid levels. Was assured all was taken care of. After bringing it home and putting in garage to install extras. Electric brake control, Goosneck hitch In bed , 50 gallon fuel tank. ect. I checked the front and rear diff. I could not find any oil on my little finger after inserting into second knuckle. This is as far as my fat finger could reach. The front inspection plug was backed out about 1/4 inch. Not in and snugged up. Needless to say I was very annoyed and had a serious discussion with service manager. They had to add two and one half pints of lube to the differentials. This is after they had assured me that all was checked and declared to be ok. It pays to double check.