1965 Pontiac 421 engine, The block is for a 1965 B-body 421 338 Horsepower Turbo 400 single 4 barrel carb 4 bolt main motor, it is stamped on the front 716753 YH and on the right side of the motor has 9778791 GM6 cast on it. the date code is G205. Two sets of heads come with the motor the first set have big combustion chambers, have date codes L020 and G020 and casting # 96. the second set have small combustion chambers and are date coded K158 and K128 and casting # 62. The crank is a ARMA steel 4" stroke crank casting # 9783787. The rods have #18/#312 on the beam. The block has been cleaned and shot blast, been bored and honed, line honed, final cleaned, new cam bearings have been installed and all new plug have been installed! crank has been checked and polished, and oil holes deburred and chamfered. rods have been glass beaded, resized, aligned, and have ARP bolts installed. The first set of head (96 casking #) have been cleaned and shot blast, have bronze liners installed, complete valve job, machined for .530 seals, have rocker stud, milled and assembled. Rotating assembly has been balanced. motor comes with New ROSS pistons new Speed Pro Rings, new Cleveite rod and main bearing, new ARP main cap stud kit, Pistons have been installed onto Rods. All machine work has been done us, at Jenkins Motor Parts and we can finish assembly on request for additional cost or buy as is. Thanks 330-938-6645