Dale - you stumped me.
Not 100 percent sure of the meaning of "RPD". In times past it has been explained to me by self-annointed experts that RPD meant "replacement parts division" OR "Rochester Parts Division". I have never seen a definative answer on a GM document; so it might mean one of the above OR it might mean something else. And since I don't know, I won't speculate on the meaning, although I have my own opinion.
The "K7" is a date code meaning either the 10th or 11th month of some year ending in 7. Since the 574s was not produced as a service carb (the 684s was used as the SR), the 7 probably represents 1947. This is the typical A=January, B=February, etc., etc. code. The reason for the vagueness concerning 10th or 11th month is that in some years the letter "I" was used, and in some years it was omitted.
The "cut-outs" were inspector stamps. I do not have a cross-reference of the stamp code to the stamping inspector.
Bottom line is this is one of the Chevrolet (or GM) produced carburetors.
And I apologize for the incomplete answer. While our library of Carter (as well as other original carburetor manufacturers) information is pretty good, we have less complete information from the car manufacturers (except for Pontiac and Oakland).
Perhaps someone else will have "RPD" on a GM document such that we may all learn the exact meaning of RPD.
Jon.
