At least 1 4x4 RST was built by either the factory or for the factory, it was white and registered on a G reg, I think collins might have had some input maybe later tho, I do have some pics that of it when the car was in performance ford in around 1990,
It had a very rare transfer box that was made for the car, from what I can remember without going in the loft for the mag anyway!

steve