Its simple, you look at the number stamped on the red cardboard tag
Seriously (yes, they once did have a red cardboard tag):
125s - short, large diameter accelerator pump
136s - tall, small diameter accelerator pump
150s - tall, small diameter accelerator pump
THERE ARE OTHER, NON-CHEVROLET VERSIONS OF THE RJH-08 CASTINGS!
The internal calibrations are all different in the 136s and 150s; because the 150s has a larger venturi.
The "C" on the casting means the carburetor was produced by Chevrolet in the Bay City plant (under Carter license).
Those carbs actually built by Carter do not have the "C".
The 136s can be converted to the 150s specifications by changing the venturi and all of the jets. Unless you have the special Carter tool set, you have a 90 percent probability of breaking the venturi and all of the jets anyway. If you do have the Carter tool set, the probability of breakage drops from 90 percent to 89 percent
(actually, probably 60 percent).
The two most critical pieces to examine when buying the Chevrolet version of the RJH-08 are the bowl and the float. Everything else in the carb (while expensive) is available.
And would you really believe an Ebay seller if they listed which model they were selling???
Jon.
