NDDan
Guest
You should gain 25hp to play with. You would gain quite alot if the '99 doesn't have the extended cylinder bars yet for they were standard by time the 65s come around. The 65 could have the high wide seperator grate factory installed which will likely help you out to some extent. The 65 may also have smaller feeder tention drums that could help you to some extent. Maybe the 65 has the 14" unloader also which would be nice. Otherwise alot of the machine would be similiar. Take care