Wow! I can’t believe that LMC Truck Parts Catalog wouldn’t have a replacement filler neck hose for that truck; I would think they’d carry just about anything under the sun for older trucks, of any make or body-style. If they don’t have it, the only other thing I can think of is trying to get one special-ordered through a Chevy dealer. As far as aluminum reacting with the gasoline, well, I would tend to doubt that, since many engines today are either all aluminum or at least have aluminum cylinder heads. I hope this will give you some helpful ideas, but I’d say also check with a mechanic for a professional opinion.