I have 2 454 1 piece rear main blocks in great condition. 1 is a Gen V and 1 is a Gen Vl. the only difference is the extra bolt holes in the lifter galley for the new style lifter retainer on the Gen Vl. They take the same cam,timing cover,crank and oil pan. Both are standard bore with no wear and a fresh hone ready for assembly....$800 ea.