Well I guess the mystery will continue! I'm not surprised they are not Slingerland seeing I have never seen an option for die cast in any Slingerland catalog. But I also do know this man did not change these hoops seeing how surprised he was when I took the floor tom batter head off and he stated "that's the first time that head has been off that drum".
I have also had numerous Gretsch kits with die cast hoops and I agree these are not Gretsch. The snare gates in the snare hoops are very large and rectangular compared to Gretsch's small, almost oval openings.
I do however find it interesting that two Slingerland owners have contacted me saying their kits had the same die cast hoops in 1961 though.
For now they will remain on eBay. If anyone on here is interested in them, contact me and we can work out an "off eBay" deal.
Mike