Your correct they are difficult to model as they are unique, both 4401 and 4402 are ex Br Mk2b FKs these coaches were completely gutted and rebuilt buy IE using new and replacement parts so Thaler had bits of everything on them 4402 had roof hatches fitted similar to the later Mk2 c/d , it also had a replacement door off a mk2d with vent at the top of the door very unusual.