I work in the wholesale petroleum industry. Ethanol is very destructive to fuel systems that sit for prolonged periods: 1) It is hydrophylic (water loving) and attracts moisture from the atmosphere into your fuel system, and 2) it is quite corrosive - you should see what it does to our pumping equipment! For hobby vehicles that sit a lot in winter, by all means locate a source of ethanol-free ("clear") gasoline for your old truck.
For a list of such stations visit this web page and click on your state:
http://pure-gas.org/
