I started a spreadsheet of D4 parts that I used on my RD4, their orig.PN, the newer PN, cat list, and source price. These prices are 2-3yrs old, but close, and show the diff between cat and other sources. This is a pdf file, so you can download it. It can be added to whenever I get more numbers needed from y'all.
Also, cats part# system now uses 4digit+ numbers, so any old parts like 4b72 would now be 4b0072 to cat.