In a std carb kit for a 235 engine, Rochester B, there are two air horn gaskets. The carb rebuikd kit illustration, shows the one to use is the one that has sort of a small dog leg cut-out at the end opposite the needle-valve seat assy. Where is the other one used. Possibly a BC? Then I've researched the Old Car Manual Rochester parts list, and I find the p/n for that gasket is 7004480 for just about all 50's carb B's. I don't understand. Can anyone chime in and help me out here? Thanks.

The gasket that is more open in the center is for the low cover 1950-1951 carburetor. The gasket that is more solid in the center (smaller openings for the floats, etc.) is for the high cover carb.
The low cover slopes down to the bowl. The high cover it about 1/4" tall on the outer edges.
The low cover had a lot of problems.

Thanks for the help. I just don't understand why these kit makers just don't come out and tell you these things. Seems like such a simple thing to do.

Talking to the larger carb kit packers shows that they actually build the kits to be used by experianced mechanics working in a regular auto repair shop, even though a goodly percentage of the final customer may be a DIY hobbiest. There are a few like The Carburator Shop that understands what we DIY users need.

The Carburator Shop web site