Based on all the aluminum mounts, I'd say your kit is a 1968, possibly early 1969. The aluminum Setomatic wasn't around very long. However, it's odd that it would have the newer style bass drum T rods. There's always the possibility that the torpedo rods where changed out for the newer style. Still, with Slingerland, anything is possible!-Mark
According to Dr. CJ Wenk the aluminum set-o-matic was used through '69 with the transition to chrome occuring in late '69 and into early '70. Therefore, based on the aluminum set-o-matic, this kit could be from '68-early '70. Serials 226xxx would be expected to be '69 with late '68 or early '70 still possible.
