I want to increase the grain tank size on my 850. I owned 2 850's, one had the 40 bushel extension and in order to fill it they added about 12" to the clean grain elevator. The other one the dealer added about 10" to the top of the bin; however, when the extension is filling up the grain starts to backleg resulting in only increasing my bin size by about 15 bushels. Rather than adding a piece in the elevator I am considering bolting the 45 degree JD style fill auger to my clean grain elevator. I ran a JD 6620 in 32% corn last year and it would pile the corn so high it would run over the bin on all sides. I think with this set up I could add an ever bigger extension without putting any more stress on the clean elevator drive. I would like to here what anyone out there thinks of my idea or what they might have done to increase bin size.