Yes, this is a Graham & David Morris conversion (All-grip traction from Builth Wells-Mid Wales).
Ford & Fordson mag did a story on them recently.
I've done my own research into converting my Major to 4wd, and this is how I would do it, if I was to do it, which I probably won"t.
I can't afford a genuine Roadless Major, but with good tyres and intelligent driving, I can get my Major just about anywhere I want it to go. For those other places, I fit my dual wheels. If I still can't get there, I don't need to go there that badly.
(Intelligent driving should not be confussed with driving in intelligent places

)
4wd would only be an advantage about 15% of the time I drive my tractor, so for the other 85% 4wd would be more of a hinderince. IMHO
Would still be nice to have 4wd though.
Kiwi Kev