Pictured above is an NOS example of the B-6763 improved oil filler pipe and cap used on 1932-34 Model B and Model 40/46 four cylinder.
This filler pipe is considerably larger diameter than the stock Model A pipe, except where it is pressed into the engine block. The purpose of the larger Model B pipe was to reduce oil blow-by through the pipe. This pipe will also fit a Model A block.
The Model A pipe was a smaller constant diameter and went through a few baffle design changes trying to address oil blow-by.
Also this cap has a copper wire screen soldered into the top to prevent any insects or large contamination from entering the crankcase.