I own a 2020 U 800. It just turned over 1500 miles. Last couple times I took it out I noticed that it had kind of a low rumble or moan when it was in four-wheel drive, it's not that loud. Having the axles locked up makes no difference. The only time it isn't present is when it's only in two wheel drive. So my question would be, could this be a wheel bearing? If it sounds like anything else that anybody knows about, please point my nose in the right direction.