72 1 = 72nd day of 1971. Or March 13th, 1971. As for the other number/letter, I can only assume it pertains to shift, etc..
I believe the 5044756 is the GM Part number. Quite common motor for cars with recessed wipers. Most, if not all GM lines used this motor. 72=day of Year Manufactured. 1=Year Manufactured, 1971 4B=Delco internal plant code for quality control, probably plant/line/shift.