no such thing ever fitted to any ma boxs in UK.
the right solution is to get a C/R gear kit £1200and use lowest std ratio you can find ,or get a gripper lsd +crown wheel + ,pinion -still lot of money there are no cheap ways .
the lowest std ratio ever used was in a 4 wheel drive ax --only lhd drive ,--good luck finding one
the lowest std ratios have been 14/60 and 13/59 crown wheel + pinions in uk cars.