I put a LSD in my old Escort. Think it was about £140 for the LSD and a day on the drive to fit it. I was sceptical but fitting an LSD was advice I was given by friends from Canada who did it with their winter cars.
If you're sticking to the roads there are few reasons in the UK that'd justify a great heaving 4x4.
If you're sticking to the roads there are few reasons in the UK that'd justify a great heaving 4x4.