6038 & PDO

["Paul Dorsey" <dorpaul@negia.net>]

Upon cleaning up my SU H6's I discovered their numbers varied slightly and I
wondered why?  The number cast onto the carb bodies is AUC 6040, however, on
one of the carb's a hand-etched 6038 is directly scratched below the 6040.
The number is on the side of the carb body, and in the same location on both
carb's.  They look identical but, of course, have slightly different linkages.
Anybody know?

Also 'PDO' is cast in several locations- Previous Damn Owner?
Thanks,
Paul Dorsey