Cub Cadet doesn't use Briggs motors. They use Koehler or Kawasaki depending on the model. I have no idea about the transmission and differential. Diff's do seem to break and be a sore point.
The company I retired from had a big lawn. For decades we used a Massey Ferguson tractor. They sold it for some reason, along with all the attachments. Then bought a homeowners style rider to cut 14 acres. The owner liked Sears, so that's what we bought and broke. Some actually lasted a full season and then some. Many didn't. I guess the $1000 price tag was attractive. So when the last group broke, we just pushed/pulled the one that had given us the best service into the boiler room and left it. The following season we started an new chapter. We bought one of their better models, with the warranty. And we broke it. To cut the huge lawn the maintenance man would run it wide open. And invariably he'd bounce it and the rear end would break. Then we'd load it in my truck and haul it up to the owners house so Sears would come to replace it.
They may be stupid, but after a while they got the idea and just delivered anohter, saying we were on our own. That one didn't last 2 cuttings. It broke and got pushed into the boiler room. We hired a service to do the work. Everyone forgot about the mowers. So just over 3 years ago we had to clean out that room. Our route boss (and a good friend) asked me about them. With him I was honest. I told him to take them home if he wanted a project. He managed to sneak the new one out and took it home. When he used a fork lift to move the old frozen up one, someone complained about him stealing it. I got wind and suggested the complainer take it home himself. He didn't want that, he just didn't want anyone else to have it. So my buddy got smart and just left it at work, in the way. He fixed the nearly new one and cuts his mothers yard with it.
The drive train can cause trouble if its abused. Running wide open constitutes abuse. So does weighing 300# and bouncing it. Riders are expensive and should be carefully handled. I read the stories about the mowers lasting 20 years or more and I can't imagine it.
