Come to find out later on, after my B7100 was sold off when the dealership closed its doors that year, a guy that bought it at the auction said they had changed out the front tires out for some unknown reason and put the wrong size tires back on the tractor before delivering it to me and caused the 4x4 to severely bind up. Apparently, it was just enough size/height difference in the tires to cause it to snap the pinion off when in 4wd. To bad, it was a really nice tractor otherwise, wishing i still had it, but fixed. Mine was gear shift, not HST. One thing i do remember, it didnt have power steering, that was the only thing i didnt like about it.