Bill, I suppose you have the muffler inlet and outlet in the correct position. If you do, drop by Advance, O'Rielly's ect, and check out the short adapters they have on the shelf.
If your pipes are still off the truck you could take them to a local muffler shop and have them "stretch" the one needing to go bigger but you'll still have to get an adapter for the other end....
EDIT: time for another chicken sandwich or maybe a hot dog this time. Give me a call one day.
Last edited by Achipmunk; 10/13/2015 3:23 AM.