Not sure which discharge you are talking about (Metal chute directly connected to loader or an actual piece of extension hose/pipe.)
Anyways if its just the metal one they are usually connected via nuts and bolts and Ive seen some where people have welded the nuts on and used thumb screws for quick release.
As for the extension hose to reach the truck my 25 hp billy goat uses an adjustable clamp to secure the suction hose. The clamp is like these http://www.directindustry.com/prod/c...57-134008.html
The billy goat part number for a 12 inch quick clamp is 791065 if you can't find one locally your dealer could order it.
Hope this can help you