chassis numbers

[BONNILA@aol.com]

My 1968 MGC GT has several factory numbers in the engine bay.  Stamped into
the metal are the following: 0CD1U 3297G and, a few inches away 500890. Also,
an aluminum or tin "Commission" number badge is attached, with G 52D 001635 P.

Does anyone know which is the chassis number?  What does Commission mean?
Thanks for any help. By the way, some of the characters are slightly obscured
or scratched so my alphas may in fact be numerics, and vice versa.

Steve Yaffe