Was doing a little preventative to my '52 GMC 3/4 ton today and when I stuck my pinkie into the fill/level check hole on the differential it came back with the color below and a bunch of tiny bubbles. When this happens in the engine's oil pan you hope for a failed gasket and pray it is not a cracked block. Color of the lube shown below.
The rear end is a circa 1968 GM 10 bolt with a 3.55 gearset. I had it apart about 3-4 years ago to replace an axle bearing that was starting to make a little noise. I wouldn't swear that I have checked the lube level since then (maybe 15000 miles), but I don't remember driving it through deep water. It does get driven in the rain though.
My plan is to drain the lube by pulling the two lower bolts of the rear cover and let it drain for a few days (not sure this works on my differential), put the bolts back in, fill to the proper lever and monitor the system. Or should I pull the rear cover and "wash" the innards? If so, wash with what?
'57 GMC 102, Original 347 V8, HydraMatic, 3.08 rear gear, added A/C, disk front brakes, HEI, AFB carb, '98 Honda Black Currant paint. T-boned and totaled 10/12 '52 GMC 152 Stake Bed, Original 228, SM420, added A/C, HEI, disk front brakes, '67 Chev 3.55 rear gear. Gets used as a real truck.
