A couple years back I acquired a great Club Date kit in BDP with a variety of different year drums.
While I know the 8x12 is standard with the CD set up, I also received a beautiful 9x13 as well.
The serial number 635131 dates to 1968.
I do not see any cataloged kits that may have had a 9x13 with them from that year though the earlier Combo did but by 67 it was an 8x12 as well.
The bass drum is a 14x20 SN-644834 from 1968 as well. Both the 68 drums have the clear wood interior & no paint.
The option of either or both is nice.
Just a one off due to the volume of drum being produced?