In fact here is another I installed over the weekend on a used gear set for a buddy on a budget. Remember I only have experience with Russian made lsds made by Val racing . Can't comment on others.
OK. I'll reply to this given I've been using them for 10 years now. I refer to Russian made torsen and clutch type lsd's manufactured by Val Racing. I too was a little skeptical so sent the torsen spur gears to get tested. The results were excellent according to the test lab. Can't remember the exact Rc hardness but we're very consistent. Machining is excellent as is finish. I've been running a couple on the track and one on dirt for over 5 seasons without maintenence. I recently pulled my road going torsen apart after 10 years street and hill climb use and gears were consistently bedding, no noticeable wear.