I knew that S/N's < B250000 had the IC version Vertical Output Amp
I checked my early 465 manual (070-1330-00, 1972). It contains a change notice and detailed section that announce and describe the change to a discrete Vertical Output Amplifier for S/N's B040000 and up.
This in contrast with my earlier assumption that the change didn't happen until somewhere
up from >= B250000.
Raymond