OK, finally found the guy who knows present Ford diffs at the Ford Dealer!!!
The 11.5" is made by Dana. A Dana 80. But Ford stopped using the Dana 80 in SRW trucks on March 24, 2010. The reason is that the parts for the Dana are twice as expensive as the Sterling. There may be some 2011 model year trucks with the Dana depending on how many were still in stock when they ended the contract.
Now, both F250 and F350 SRW's get the same 10.5" Sterling rear diff. The only difference between the 250 and 350 is the 350 has a stiffer spring rate.
The F 350 Dually still gets the 11.5" Dana.
