I was transporting my M59 Kubota tractor / loader (approx. 8500 pounds) with my dually six speed 3500, when my transfer case went into neutral while going down a steep incline!!! Could not shift the floor lever back into 2wd (grinding), had to get to bottom of hill, pull over, come to full stop and shift into 2wd. Not a fun experience especially when you can't down shift to help slow you down, only service brakes (unfortunately no exhaust brake either!). During the course of the day this happened about five times, on flat roadways also. The lever " feels" slopy, very easy to shift in and out of 2wd and 4wd. I'am I looking at a new transfer case? Or hopefully, some adjustments to the linkage? Got home way after dark to investigate problem, plus had to go change my under pants ( going down hill episode!!!). This has never happened before, I've towed this tractor at least one hundred times this year without any problems!!! Any advise would be greatly appreciated. Frank