MO2AZ,
Check out
http://titanfueltanks.com/products/mid-ship-fuel-tanks for a larger replacement fuel tank on that super duty. We have put several of these in customers trucks and have been a great product every time. A nice thing about these tanks is they fit in the original hole under the bed and they use the factory fuel pump and sending unit, so if you ever have a sender go out on a trip you don't have to wait for some special part to get shipped in. I have also had to get replacement parts for an older Titan tank and the customer service from Titan was second to none. Highly recommended!!
