I won this on Ebay recently:
I think it might be a pre-production version but the only orange-bodied one I can find is in the 1992 catalogue and that has the plain black chassis and no decals. As I understand it, the last use of the "Shawnee" decal was in 1987 on the blue one with 6600 tyres sold with the Massey 2680. The Rear Dump briefly ceased production, only to come back (by popular demand?) in 1992-1995 with black chassis and a green/orange body. Only other explanation I can think of is this one was taken off the black chassis and put on the old red chassis, though I don't think that can be done without breaking it (and there are no visible break/scuff marks on this one).
Does anyone else have one similar to this?