Does “MB” below the power cord mean...

That a Mk II has had the loop mod?
Looking at a IIB and trying to get one that doesn’t need the mod.
Thanks!!!

No, MB written in sharpie under the power cord means the amp was put through test by Mike Bendinelli. Who tested MOST Mesas in the Mark series.

A smaller number have RS written instead of MB. RS means, yes, Randall Smith.

Thanks!
New to Boogies and trying to buy the right one the first time.
Do subsequent dates below the power cord mean anything on a IIB? Looking at one that has three sets of dates electro-penciled below the cord. IIRC the years are 84, 87, and 90 on a 82 serial number. There are full dates - but these are the years.
How does one tell if the amp has the loop mod?
I’m searching this board as well, but I may be asking too specific questions because I’m not getting a lot of answers, so any help from the Boogie vets is most appreciated!
Thanks and regards,
RD