I've changed a Vulcan undercarriage in an 8 hour shift (with time to spare) and it's not that difficult to do with the right tools and GSE.
As a former Vulcan SEngO I'd say that was going some, especially if jacking and de-jacking is taken into account. Maybe as a planned second/third line task with everything planned just right you could. Even so, I would have been impressed if I could have had that done in 8 hours by the ME(A)S guys in my day.