I'm going with an alum and mounting it in the bed of my 1998 Sonoma stepside. They also come with a GM sending unit and don't cost that much more than a plastic one. I don't think they come with foam however, especially the one with the sending unit.
Summit has them in all sizes up to 20 gal. the 10 gal has foam, @ $165.00, the 15 gal has foam and 90 ohm sending unit @ $249.00
Zip.