My 49 6400 truck has a two speed differential and is running well. When I first got the truck two years ago I checked and topped off the differential fluid. Today I noticed that the pinion gear housing has a fill plug. I checked and there is fluid in the housing. Following disassembly and in the reassembly process the shop manual says to add 1 pint of gear oil to the pinion gear housing. I have never had the differential apart and in only looking at the drawings in the shop manual, doesn't the gear oil from the differential flow into the pinion gear housing thru the bearings. The book never mentions checking the fluid level or gives a level to maintain in the pinion gear housing, so that is why I question the need to add any fluid to the pinion gear housing if you have never had the unit disassemled. Am I correct in my assumption that keeping the gear oil at the proper level in the differential will properly provide lubricant to the pinion gear housing?
Jim
