Zenstat - thanks for the reply and feedback - very helpful! Yes the 18" bass drum is 16" head to head, a bit under 19" outside hoop to outside hoop - unusual for sure. Maybe I should call is Jazzette-like?

Are you sure that you serial numbers are 6 digits and not 7?

Mike - yes, they are all 7 digits - thanks!

Does it have a rail mount for the 12" or a center post? I think I can see part of the center post bracket in the picture.

16" depth is a bit of an oddity for a bass drum in the 3 ply era but not unheard of. It is a standard sized shell for a floor tom so easy enough for Ludwig to build a bass drum out of one of those shells if someone requested it (same shells anyway). The woodgrain cortex wraps first pop up in the '73 catalog (probably put out in late '72) so that helps a bit with a timeline although your serial numbers would seem to put these squarely in the Keystone badge era, around 1965, which is not possible given the other visible details of the set. Another oddity. Any possibility the "professional drummer" you bought them from was a Ludwig endorser? That might explain the odd serials and unusual bass drum size as an endorser would have easier access to specially made setups and also might get "prototype" badges that were out of sequence.

Hi - sorry for the confusion on the serial numbers - I think the first 3 digits identify the era, but I didn't pay attention to the number of digits. They are 1174638 tom, 1087153 floor tom, 1083704 bass drum. And yes, the tom mount in a center mount - I've enclosed a picture - thanks!

Yes, looks like the serials are in the '73 range as well.

Sorry I misread your answer to Mike I thought you said they were 6 digits. My bad.