the gmc family of engines (228, 248, 270, 302)are all full oil pressure engines. they use insert bearings. There is an engine number stamped on the flat spot just behind the distributer. The first 3 numbers tell you the displacement. If the engine was from a 1/2 to 1 ton pickup, it is probably a 248. If it was from a larger truck it is probably a 270.
