Does anyone know when they first debuted the "classic rock" setup for Slingerland? It's not listed in the '73 catalog on the Vintage Drum Guide web site, but shows up in the '77-78 catalog.

http://www.vintagedrumguide.com/images/slingerland_drum_sets/1977-78-slingerland-drumsets8.jpg

I'm 99% sure this is my kit, but I'm trying to narrow down the date a little (which, as I'm learning, seems impossible...)

Thanks!

Troy