for some reason, this computer i am at (not at home) the resolution of the 3 pics is really HIGH and appears clearly Marcello's observation is correct, the figures are carved.
on the other two vins, can actually see the indent of stamping die. on the vin in question, one can see raised and lowered areas in the bottom of the digit's markings, suggesting the numbers are, indeed, carved, etched, or etc, but certainly does appear not stamped. the figures are so irregular, they cannot have been made with a stamp, at least a stamp of high quality.
i am going to suggest, the cases were unstamped replacements and the Evin from the original engine was placed oin this unstamped set of cases.