Gearbox for bush hog dm90 disc mower

Hello, I am new to this forum but I have a question about gearbox on a dm90 disc mower. I have had this mower for about 4 years now and everything was working fine until the main gearbox ran out of oil due too a bearing going out while I was using it. I called my local dealership and they told me bush hog does not make this gearbox anymore they just sell the parts for it, but it has been a struggle getting all the parts for it. I was wondering if anyone on here might know where I could maybe get a whole new gearbox or if someone might know where I could get parts at? I am located in central Illinois and have been dealing with Beard Implement and they have not given me very good service

Thanks

Gearbox for bush hog dm90 disc mower