I have seen 3 different Marks of Wide Track:
Mk 1 - drum brakes, front stand, no jockey wheel and no fog lights, 6.50 tyres. I had one of these, it was a GT, older than the Lightweight I towed it with.
Mk 2 - drum brakes, jockey wheel and fog lights, 6.50 tyres.
Mk 3 - disc brakes, 7.50 tyres, correct designation FV2381. I have one of these I tow with the Wolf.