Nice Jay!
Pat is right there are many scraps with only the black/brown/yellow layers with other backs.
The term yellow/browns I believe refers to the 33 known unique cards that come with SC backs. The Chase dark cap should be out there to complete, IMO a full 34 sheet.
The yellow browns do also have a red layer
I was keeping track of examples, haven't added any in the last 5+ years.
