Dan
Guest
Only the first run of 800's should need updated hold down. The original hold downs were 2.5" and then went to 2.75". Would need size of head to get you part numbers. You know the flighting to be 7" on the 800 as compaired to 4" on the 500. Otherwise very similiar and I would bet most any other changes would be for the larger sizes that have more weight turning and cycling. Sorry haven't kept up with more details of changing but haven't had much trouble with either.