I didn't want to buy a diff. from china and now that I have I regret it. The quality of their products has not changed since I bought my trooper in 2009. I just received a "new" rear diff. from Klung motor sports. When I took it out of the box It looked great but that was as far as it went. I tried to turn the pinion it would not budge, I had to use a pair of channel lock pliers to get it to move at all. I took it apart to find out why and it had almost a full shot glass of metal shavings inside. The machine work done on the ring and pinion was so rough I am surprised that the tooling used to cut the teeth even worked at all. They didn't even try grinding it to smooth it out. The only good thing they have done is they changed the carrier bearings to needle type from the ball bearings they originally had. It would have been even better if they had changed the pinion bearings too but they didn't. The spider gears are still very loose but I can't take the carrier apart too tighten it up because they have spot welded the carrier together. I would not recommend anyone to buy a differential for their trooper our any of the joyner models from china, unless they don't care about the quality of chinese products. I emailed bob at klung and he basically said to bad you bought it it's yours. It's too bad they aren't in this country so I might be able to get something done about it.