The Corvair carb were known as a model "H" with the "HV" having the vacuum pull-off. The monojet is the model "M" and "MV". Rochester also had a model "R" and "RC" (sidedraft 1 barrel), but these are seldom mentioned as most hobbyists have never heard of them (and I wish I hadn't!!!).

Jon.

Good carburetion is fuelish hot air
The most expensive carburetor is the wrong one you attempt to modify.
If you truly believe "one size fits all," try walking a mile in your spouse's shoes!
The Carburetor Shop