I don't remember for sure, but the block-mounted starter probably came out the same time as the aluminum case Powerglide. I don't think the flimsy cast aluminum bellhousing for either stick shift or automatic would have carried the torque of the 3-bolt starter that mounted at the nose cone. 1962 was the first year for the aluminum case PG, IMHO.
Jerry

"It is better to be silent and be thought a fool than to speak and eliminate all doubt!" - Abraham Lincoln
Cringe and wail in fear, Eloi- - - - -we Morlocks are on the hunt!
There is nothing noble in being superior to your fellow man; true nobility is being superior to your former self. - Ernest Hemingway
Love your enemies and drive 'em nuts!