Only one of the pre-war clasp-braked LNER 5 plankers (a la Parkside) was known to have passed into Clayliner use, although there were probably some of the post-war 5 plankers with RCH brakegear and certainly some of the 6 plankers. The latter would either be a scratchbuild or an extensive conversion from something like a 3H or Cambrian wooden-underframed version.
The LMS, SR, MoS (again only one) and BR dia 1/034, 1/042 and 1/045 5-plankers are much of a muchness apart from small details and personally, I would use the 1970s Airfix RTR item (since made by Dapol and now Hornby), although the above mentioned Parkside body is very similar.
As well as the roller bearings, I would expect that most if not all wagons would have had BR-pattern axleguards fitted at the same time