I ride through sand, mud, and climb some serious trails. Ive been very surprised how well the diffs have held up on these units. I did strip the spider gears in front diff and just broke a rear axle last weekend. I was in a soggy sandy creek when my front end went. In my defense, I noticed clearance issues in the spider gear factory setup, but I'm sure it was operator abuse.. Lol. The rear axle broke climbing some logs off trail on a night ride. I hit it a little to hard! Most of the time I engage 4wheel drive but I hardly ever like to engage the lock on them (suicide button)..