New school of thought:
Viton not necessary. New OEM fuel hose will work just fine. It's not the rubber compound that makes original fuel hoses break down under biodiesel use. It's the fact that they're 20 years old, so the bio serves as the straw that broke the camel's back. Viton is way more expensive than regular- if you want to save a wad of cash, just buy new regular hose.

__________________
'02 BMW 325i
'85 300D 450k
'93 190E 2.6 170k(killed by tree)
'08 Ducati Hypermotard 1100S 6k
'06 Ducati S2R800 14k(sold)