JB-My guess is they are clueless. Case in point- received this months edition of Work Truck Magazine and once again, there was a Ford Commercial Truck flyer included. One thing I noticed was for 750 they list a a max GCWR of 50,000 pds. In the old days, (KTP era) you could get an F-700, and F-800 with a GCWR of 60,000 pds. And an F-8000 with a 3208 Cat carried a GCWR of 75,000 lbs. The F-700 would have had a max front axle of 9000 lbs and a rear of 19,000 pds while the F-800 and F-8000 could be built with a 12,000 front and 23,000 rear.
Looking at todays 750, you can get that same 12 front and 23 rear. The frames are in essence available in same ratings (SM and RBM), and I'm sure the wheel/tire ratings are the same. As for cabs, while some say the current 750 cab is a "Pick UP" cab, I would bet it is far more comfortable than the old F series cab. Now in the old days, many carrier used F models in their P & D operations-and I'm sure many a day those city P & D tractors went out with a 40-45 box that pushed that 60 or 65,000 lb rating. It was a cost effective alternative to the L/LN series of competitive trucks from GMC, International etc.
So why do the new trucks carry a lower GCWR rating? My bet is Ford does not have the confidence in the 6.7 Power Stroke/ Torqueshift combo to support 60 or 65,000 pd. ratings in particular when you are pulling a 13-6 box height with all of that wind resistance.
Again a solid case for another engine/trans combo that could provide incremental sales of 750 without a lot of engineering cost. I guess they just don't see Avon Lake utilization as a serious issue.