ac6000cw
Established Member
Don't forget that the prototype HST was, for a little while galloping around with a Mk1 buffet in the formation (suitably painted to match the rest of the set). It rode quite happily on it's B5 bogies.
Also when WCML 110 mph operation (with class 90s) was first introduced the Mk1 brake vans were used at 110 mph with 'special maintenance'. These were later replaced with new-build DVT's.