That`s late 60`s and should have date stamps inside. If they were sanded before, you wont find them. No serial numbers matter, Sonor kept no records on date`n products. Everything about old Sonor had to be figured out the hard way, mostly by member Henk !i (he`s the got-to teardrop guy)
Those are six ply and a bit mickey moused. The tom mount on the BD belongs to a double tom holder and the original one should be a internal boat mount like on the tom. There is a difference in thickness with the BD but not in plies. I have nine ply Phonics but can`t count most of the layers. I did however wipe a damp cloth on them and realised that you get a better indication of plies. Some you can see, some you can`t. Anything Seventies+ wont fit without drilling something !i (except threading)
The wrap is toast on the tom and BD. I can`t see the FT too well. If the FT is good, save it, wrap and all, and trade or get another to wrap if you decide to go that way. Drops are sought after !i
Except for the BD, everything else looks un-altered !i
The difference in colors is the blend of sapwood and heartwood. Sapwood will be the exterior ply if the drum get`s a wrap and heartwood will always be the interior. The one you show has two thick plies on the inside and outside, and four plies sandwiched in between them !i
Clear shots all around and inside each drum,..and you`ll get all the info you need. The hoops and T-rods are getting harder to find but do show up so be patient !i
