Short answer - check out the Rogers book by Rob Cook. (Do not have my copy in front of me, so using online info)

Long, but still short answer: Mostly CBS ownership for cost savings. Many of the changes were done with the move to Fullerton CA around 1968-1971.

T's and Claws... late 1966 change to the "Batwing" as some call it. Patented by Jos. B Thompson/ Rogers.

Floor tom leg mounts. first pic. is a Fullerton era Cast Knobby. Second pic is the machined version. 1959-70/71 for the machined version, 1970/71-1978 for the cast version. Third mount was the Memriloc … same footprint, tubular legs.

Tilters.... Left... machined version 60 or so to 1971 at least. 1970 catalog still shows machined. Right... integrated, 1971-1975. Next version was Memriloc to 1984.

Tom holders... Londoner style.. 59-71 or so for the machined version, different variations depending on its use and style, Integrated version 71 or so to 75. 1975-84 Memrilock ratcheting style.

These answers are very basic. The Cook Book would be a good thing to grab... Rogers, second edition. I recommend it.

Anything built after April 1966 was CBS era... to the shuttering of the doors in June 1984. Some of the changes were good changes. Some not so much. All of those pictured, while they might not be as aesthetically pleasing as the earlier versions, they saved a ton of money and kept cost down to a reasonable point. The only thing they really struck out on was the Collet Tensioners being changed from machined to cast. That was a failure.

Thanks so much. Very helpful. I'll be finding a copy of Rogers book by Rob Cook.

Thanks for your help. I really appreciate it.