Actually there are four carburetors for 1927.
The RX-0 is completely different from the other two and used on the early '27s. It has a body with cast in venturi. Multijet (aka main jet) with center orifice and smaller one at a 45 deg. angle to regulate fuel to main orifice. It is a Carter model number 4s or 6s (with adjustable multijet similar to model A Zenith).
There are to different versions of the RAJX-0. The 85s is the first version with removable venturi, well jet and auxiliary jet to control fuel flow to low speed jet and and mulitjet. It has a standpipe without any holes on the clever section. There is also a 111s that is similar to the 85s with three holes on the clever section and a sliding tube attached to the throttle plate similar to the RAKX-0 (102s) used on the '28 Chevrolets. The 111s is apparently a later (after production?) variation.
If you want to count the prefix C carburetors that were produced in a Bay City Michigan plant operated by Chevrolet and the non-C versions produced in the Carter St. Louis plant that makes 8 carburetors for 1927.
