Just for what it's worth...
I have just disassembled what I think is an Airtex 4036, which looks like an aftermarket replacement for the AC 4036...
I think based on the condition of the diaphragms and the valves this pump would have worked fine for several more years.
The bowl and filter screen were pretty dirty, and the only problem i saw was the intake valve had stuck itself closed and so the pump may or may not have worked...
But I would have no problem installing an NOS pump even if it were 60 years old...as long as it hadn't been stored outside...