When looking up the serial number for the rear shock on my Pivot Mach 4 SL v3 (Part 972-05-949: 2025_24, FLOAT, F-S, K, 2pos-Adj, Evol LV, Pivot, Mach 4 SL MD-XL, 190, 45, 0.5 Spacer, CM, RM, CMM, No Logo, OE), the specs indicate that part number 803-01-993 is needed for rebuilding the air sleeve. I was having a hard time locating these, and after some digging it turns out that there’s a replacement part number for this, 803-01-727.
Per Fox:
That is the permanent part number moving forward, as both part numbers contained the exact same seals so we consolidated to one PN which was the one I referenced, 803-01-727.
(It seems that some of the entries on Fox’s site still show the old and hard to find model number, so I’m making this post to help others who might be having a hard time finding a seller carrying the originally-spec’d part.)