QHBH additional bracing

                               Hi all
                                 Noted the other day some of the new QR QHBH coal hoppers
                                 had some additional horizontal bracing
                                 There where plenty of new QHBH hoppers but only
                                 3 two packs (that i seen) had the extra bracing
                                 the numbers are                                  
                                 QHBH
                                 55619E/55618S
                                 55617J/55616A
                                 55613T/55612K
                                 Note in the pic the varying heights of the bracing 55618S and 55613T