I present a Tektronix 5031 oscilloscope. Near 1968. True dual beam (chopper or alternate not needed), display splitted into 2 memory array, very high sensibility (10uV) and differential input, but low frequency (1MHz), direct input for current probe (I don't have).
Photo 2 shows memorized trace.
Photo 4 shows an input rotary switch, small switches are directly on board.
Photo 5 : there is one hour counter in the scope (on the left, near transformer), can be reversed (by reversing polarity) if made before indicator reaches one end. Too late here !
Photo 6 : we can see the size of the time base rotary switch (cover not removed) !