Im still drive the stock rear beam and axels, whats can be a good optional.
One option is the Eaton plated LSD, which runs about £275.
The weak point in the stock diff is the spider gear, of which there are two. I know with the Eaton LSD the spider gears are designed with a backing plate that greatly improves the strength, and they are forged and shot-peened. The point? With an aftermarket diff you'll probably support much more torque than stock. If you install a Quaife the spider gears are eliminated altogether and the next weak point becomes the ring and pinion, which members of this board seem to have no trouble with until they're up to ~500hp. Not many people get into that territory.