I think 55 pontiac was the first to use one that resembled the modern BOP, but it didn't become a standard until the mid 60s, like 1964ish with the midsize GMs. cad and buick were still funky thru 1966. So I'd say they were finally standardized in 67, but that's not really what you asked.
'55-'60 Pontiac was its own entity; in '61, it changed to what eventually became the "B-O-P" pattern. All of the '61-'63 and some of the '64 Pontiac blocks had no provision for a block mounted starter.
The Jalopy Journal
