UMGF is the popular Unofficial Martin Guitar Forum:
https://umgf.com/
I would assume SM means Stewmac.
I know stuff like that is hard to find though. I was looking for 1930's OM plans last year and found only one plan online which was offered for free. Of course it was only a small print out on standard paper but still had all the dimensions. I'll try and figure out who that was as he might have a Dred too.
EDIT:
Found it but there is no Dred.
http://www.grellier.fr/en/downloads