An engine oil leak may develop from the distributor shaft o-ring seal.Google+
Car Problem Reports
GMC Sonoma Distributor Shaft O-Ring Seal May Leak Oil
GMC Sonoma Problem
Engines Affected: 2.8L V6, 4.3L V6
Average Mileage: 175,678 mi (170,357 mi - 181,000 mi)
Visitor, 1993 GMC Sonoma, 2.8L V6, 181,000 mi
Thought I had a rear main seal leak. Found that oil was weeping out from under the distributor. Put a new O ring seal and a distributor gasket from a 350 and the leak is stopped.