Who sells just the diaphfragm for a common AC 429 fuel pump?

You might message carbking. He specializes in fuel systems and may have a source.

I would try here;

https://www.then-now-auto.com/fuel-pumps/

Dave

What does the 429 fit? Some of the Fords used the same style pumps as Chevrolets and the parts suppliers have the diaphragms. C & P Automotive (Billy Possum) sell some that can be used with the original shafts by drilling and tapping for a screw and washer.

According to google it fits 37-51 Chevy and 39 GMC.

The info for the pump kit for the AC 429 at "Then and Now Automotive" says:


This fuel pump kit is compatible with:

Buick 1938-39 Series 40 (1938 After 58,000)

Chevrolet 1937-1938-1939-1940-1941,1942,1943,-1944,1945,1946,1947,1948,1948,1950,1951, ALL (Standard)

GMC: 1939-49 & 1950-1953, 1955-1962

Hudson: 1939 Model 90,92P,95,97, 1940-1941 Model 10,40

Nash : 1935-3580,1936 -3680,1941-4180

Pontiac : 1937 Canadian

Willy’s : 1937-1940 All models , 1941-1942 All; Pass and Panel delivery


so I would assume the same diaphragm is used across all of these pumps and applications.