Block
#3855962 casting number location at back of block.
Beginning in 1965, when the big block engine was introduced, the early big block
engines continued to use this same format. The engine assembly code was stamped
on the engine prior to the installation of the cylinder heads at the Tonawanda
engine plant. Since this stamping was on the right hand side of the pad, only
the left side was available for the VIN stamp. The VIN stamp was always stamped
at the final assembly plant where the engine was mated with the drivetrain of
the car. This created a problem since the plug of the cylinder head, which was
also on the left-hand side, was obstructing the placement of the stamp. These
early blocks were stamped in this fashion until after march of 1965. Because
the plug was impeding the VIN stamping procedure on the left, many were stamped
in a skewed fashion just to be able to place the 
