5000CSTQ Rear Differential Howling

[Louis A. Mulieri]

Hi,
	My '88 5KCSTQ has developed a howling that shifts around in 
frequency and rhythm that sounds like a dry rear differential. I tried to 
find a filler plug on the housing but it is completely obstructed on both 
sides. There are 2 plugs in bottom of housing.
	Is there a filler plug somewhere on side? Where? What type/weight 
gear lube is appropriate? Thanks for help and advice.

Lou Mulieri
Hinesburg, VT