2 piece bridge and tail. Was something changed ?

[TonMan1]

Hi! Gibson used cast Aluminium Stoptails until the early Sixties. The "Lightening" wrapover on Jr.'s, Special's & Melody Makers were the first ones to use cast Zinc. The ABR-1 base was Zinc but the saddles were brass and later Nylon. The stoptail Studs, until the late `80's were machined steel. the ABR-1 posts are brass.
Zinc can only be cast since it doesn't ever appear in a machinable form like brass or Aluminium.

 

[László]

Hi! Gibson used cast Aluminium Stoptails until the early Sixties. The "Lightening" wrapover on Jr.'s, Special's & Melody Makers were the first ones to use cast Zinc. The ABR-1 base was Zinc but the saddles were brass and later Nylon. The stoptail Studs, until the late `80's were machined steel. the ABR-1 posts are brass.
Zinc can only be cast since it doesn't ever appear in a machinable form like brass or Aluminium.

Got it. I'm no guitar historian. I only go by what I've got.

My first guitar was a 1965 SG Special that my brother got new. Still have it.

I was going by that and other Gibsons I had in the long-distant past.