As an emergency repair I would visit a NAPA dealer and they can manually search for exhaust pipes of all sizes. You need to know the size and length of your pipes that you need. Cost is reasonable.
If you have a Freightliner Chassis and your can find a dealer near you that would be the best solution. Check internet for the closest one. (Sorry see you have a ford ch)
I have used both. Word of caution....fumes, even though in the back, will creep up to the forward cabin.
98 Endeavor DP, ISB275
RX300, Falcon II hitch, BB Vantage Select
VMSpc, 2002 Grey Ford Powerstroke
TST 507 w/ 10 Sensors