I posted this same reply in another post, but it seems appropriate to post it here:
Are you interested in original Bennett literature about the 150 literature? The reason is that Bennett did not invent/make the mechanisms, they purchased them from companies like Neptune/Pittsburgh/Buffalo. Many time the mech. you are looking for was used in a number of other pumps made by other companies.
Author, Gas Pump Identfication books 1st & 2nd Editions & Air Meter Identification books
We rebuild ECO air meters and sell parts.