Suits Late Model 1986-on with 1-Piece Rear Main Seal

GM10105123

10105123

Description This engine block is used in 1986-99 Gen I heavy-duty applications. It has 4.00" diameter cylinder bores and four-bolt main bearing caps. This block is machined for a one-piece rear crankshaft seal. These blocks weigh 197 lbs. Cylinder wall thickness is the same as current production engines. The lifter valley is machined for hydraulic roller and flat tappets. Crankshafts with two-piece seals can be installed with adapter P/N 1005118.This block includes: main bearing caps, main bearing cap bolts, freeze plugs, oil gallery plugs, and cam bearings.