Frank, and everyone.
The early mechanisms were invented by a man named Penn. He licensed the mechanism to a number of companies including ECO, Gilbarco, Air Meter and a couple of others. Not all parts used by these companies are interchangable. The mechanisms look alike, but again not all the parts interchange.
Years ago I was able to use what few parts I had to make these units work, but those days are few and far gone. Your request for a complete unit is the way to go. Good luck.