Ok, here's what I found:
1. The 1972 Walker Muffler catalog S72 showed their #21075 for 1953-55 Kaisers. This number was also used on 1955 8 cyl. Commender and President models. The same number is also listed for 1954-55 Aero Willys models with the 226 engine, the 1954-58(early) Willys 226 equipped 4WD Station Wagon, the 1954-58 (early) Jeep trucks with the 226 and 1955-58 6-226 2 wheel drive station wagons and sedan deliveries (EARLY).
2. Using the Walker information above, I crossed it to Willys Motors P/N's 735622 This P/N was still current in Kaiser Jeep books issued in 1967.
3. AP's 1964 book lists a P/N 510 for the 1953-54 Kaisers and the Aero Willys with the 226; it also gives a Studebaker part number of 536409 for the 1955 application noted in the Walker book.
4. The 1963 Maremont book lists an ST46 as a replacement for the Willys P/N and the Studebaker P/N.
Hope this is a help.