Not an F250, but my 97 F150 5.4 had a cat fail on the drivers side...there's four on the 97, an upper and a lower on each side...the upper failed, came apart, and completly plugged up the lower cat. Blew the DPEF sensor hoses off the sensor there was so much pressure. Had 150k miles on the truck...no warrenty for me.
Had to cut a relief cut in the exhaust to get the truck to a shop.
Anyway, the truck was worth 3k and I wasnt about to spend 1k on a Motocraft catalyst.... Went to Napa and they installed one large Cat in place of the two smaller ones, they also replaced the O2 sensor and I went along my Merry way.
No CEL's or any problems from the Napa Cat.
I don't think that 5.4's fail at an alarming rate, mine had 150k miles on them. I think my root cause was a fouled plug on the drivers side bank and raw fuel being dumped on the cat, but I'm not 100% sure.
Glad you have got it fixed though!
Thanks!
Jeremiah