Napa or truck service
This is not difficult, contact Napa, year make model, they have a great system that may have a listing.
Next check truck supplies, industrial rubber supplies or RV servicing dealers, many ,may have the hise in stock if it was a common type.
If no results, then check local sources for fuel hose of the diameter installed, then once a source is found, carefully remove the old one, if it needs to be cut then mark it to realign if molded.
Examine it, there may be a Gates or other part number on it somewhere.
Tony & Lori
1989 Country Coach Savannah SE