There appears to be an "easy" fix for this. I just have to proceed carefully.
( and " easy " is a relative term )
When all BTR-50's are made 20 carry capacity and changed to UC-120 that shifts these big APC's to a UC all their own. The ONLY formation affected by this is 5 ( from the POV of the picklist )...that's the Mech Rifle Co from 1/1955-12/66......none of the others are affected ...BUT......moving Formation 375 to slot 5 puts the Hvy APC's in the formation slot the picklist wants and moving Form376 to Form38 puts everything in sync.... freeing up 2 formation slots as well as changing nothing from a player POV and keeping the picklist " happy " once the "new" Form 5 is pointed at the correct place it's "new" pls are found in ( 38 )
now all I have to do is figure out the infantry that goes into each and in the end these early big carriers will be set up correctly but there WILL need to be a slight compromise to accommodate the lower carry capacity of the BTR-152 that shares this class
The bottom line is this can be fixed so it better represents the actual situation but it won't be exact and in the process free up 2 formation and 1 unit slot