I cannot answer to the GM package so I won't go to the one is better than the other thing. I am quite impressed so far with my 6.2 w 3.73 gears as it will haul 8000lbs around with no lugging on acceleration at all. With hill start assist, trailer sway control etc the Super Duty 6.2's were made to haul. The 6.2 motor is designed from the ground up as a truck motor not a passenger car engine pushed into truck duty so it has the classic short stroke big bore design of the big block 429/460 of the past. THey get decent mileage for a 385hp engine in a 7300+ lb truck and the 6 speed auto box is a gem with the full manual mode and a t/h that really works, just tap the brake pedal and it downshifts and compression brakes very effectively. I posted these links before but I will do it again.
1: Pickup truck's shoot out.
PickupTrucks.com - Special Reports
(16% Grade run)The 6.2-liter V-8 ran up the hill a full 5 seconds and almost 5 mph faster than its next closest competitor, the Silverado. Its rpm seemed to pick up faster than the Hemi’s or the Vortec’s, and it was so fast that it shifted into second gear during one run, though it lost about 1,000 rpm and immediately downshifted. During the other sprints, the F-250 remained exclusively in first gear to top of the hill approaching near redline. The whole run the F-250 howled like a muscle car, not a three-quarter-ton truck with a combined weight of more than 17,000 pounds
2: 2011 Ford Super Duty F350 New 6.2L V8 Towing 10,000 lbs. With 5 Star tuner. (Diesel guys won't appreciate the music but that engine sings like the old days of big block muscle cars)
5 Star Tuned !! - YouTube