The screws at the front, middle, and rear of each rail are called out by different part numbers in the TM. The front screw (#1) 5305-01-210-6249  with a manufacturer P/N of PL25D02P12 was not locatable.
The screw at the rear of the rail (#10) 5305-01-117-3396  was similarly unlocatable, however we were able to locate this screw by its manufacturer P/N of NAS1635-3LE12. This is essentially a #10-32 x 3/4 screw. However, this has pre-applied locking compound. Additionally, we surmise this screw probably has a higher tensile strength than a standard 10-32 screw as it is an aircraft fastener.
As for the PL25D02P12 fastener called out for the front connection, at least one vendor (Kascar/real4wd.com) lists the NAS1635-3LE12 as an interchange. (at time of post, searching for the PL25D02P12 fastener comes up as NAS1635-3LE12) See: https://real4wd.com/store/catalog/search.aspx?keywords=PL25D02P12
In other words, we are comfortable that since both fasteners specifications are as a self-locking 10-32 x 3/4″, that use of the NAS1635-3LE12 is proper. There are apparently 50 in a box, and we have ordered 4 boxes to keep in stock.