These cars are out of UMLER and can be put back under what is called an add back program
XP: Boxcar similar in design to XM, but which is specially equipped, designed, and/or structurally suitable for a specific commodity loading; except, boxcars (XF, XM, XMI) dedicated to the transportation of commodities in paragraph A, Rule 97, AAR Interchange Rules, must be designated XP.
Equipped Box Car, Inside Length: 69ft to 79ft, cushion draft gear/underframe, Sliding door, opening greater than 11 feet
67ft 11in / 10ft 6in / 15ft 5in
60ft 10in / 9ft 6in / 11ft 0in