Franklin,
You can check the part numbers with NAPA using their web page www:\napaonline.com
On the main screen, look for "Search NAPA Catalog using PartsPro SE" (on the left about 1/2 way down)
Once you're there, put the Chevy part number in the SEARCH box and click the Interchange option. Press the red X and Presto -> NAPA part shows up (or not, as the case may be).
I just checked the early '53 numbers and came up with UP14499 for the Rear Front cylinder and UP14500 for the Rear Rear cylinder. Heart stopping prices, but they are made in the USA and fit correctly.
