Ralph, thanks again. Think I'll give BW a shout and see what they think about it. (hopefully it's an uber rare prototype, that will be worth enough to get 2 new LT230s, one for this truck and one for my own )
Will be pulling the top cover off soon to sort out a dodgy reverse light switch, so will see what I find then.
Props and diffs are on the right, as normal.
Cheers gents, the mystery continues.