Norton Villiers Triumph had an arrangement with Yamaha at the time, which led to XJ900 instruments and cycle parts being used on the Norton Rotary, NVT developing the Yamaha HL500 off roader, and the supply of Yamaha DT 125/175 engines for the Tracker. It was a fairly straightforward trail bike of the time with monoshock frame, typical styling, but unusually for a the period a disc brake. A small number were built, then for some reason the name was changed to the BSA Tracker.
Again a small number were built, and if I remember correctly, some went to Africa as part of a Riders for Health type initiative, where health workers travel round rural areas on motorbikes.
It probably wasn't a bad bike, but it was in a very competitive area of the market against similar bikes from all the Japanese manufacturers (including Yamaha).
Found a couple of articles on the Web by owners of Rambers: here and here.