Ken
If you are using the truck as a DD much then I'd stay away from a 5500. Besides with your truck being a dually 6 speed, it is about as capable as any truck 450 and 5500s included for towing.
If you keep your truck and save the $25k upgrade for the new truck smell, lol, I'd reccomend a dual disk rather than a stout single disk clutch. I roasted The stock dmf clutch in my 07 at about 40k mi with a good tune and very little towing.
Put in a Southbend OFE single disk. Got 80k mi out of it mixed mostly commuting and maybe 15kmi towing or hauling heavy. Replaced with another single disk due to the economics of it and getting very good treatment from southbend.