Found it. It was in a thread re building an F550 Surf Camper over in the "Other Custom Expedition Camper" section. Here is the link: http://www.expeditionportal.com/forum/threads/141578-F550-Surf-Camper-Build-Adrift-in-the-Green-Room?p=1970128#post1970128
Owner took delivery of his 2016 V10 gas F550 a week ago after a 19 week wait and posted the info re the Dana factory being at capacity for the 110 and 135 axles. He reported that new truck orders for the 450/550 class are over 20 weeks out now.
Hopefully Dana will catch up with the demand and the waits will shorten. Having ordered trucks myself, I totally understand the frustration that the wait causes. You put your money down and commit too the order. You want it NOW!
Noodling over an F550 4x4 diesel crew cab with a custom flatbed myself to carry my Northern Lite 10-2 CD SE due to a need for a 3 foot garage between the cab and the TC so I am following your thread with interest. Currently on an F350 4x4 diesel DRW crew.