Payload rant (sort of)
I have a friend with a 2011 F250. I don't know a lot of details but it has the diesel for that year and 3.31 gears. He was looking to buy a fifth wheel after previously owning a 35 foot TT. Unfortunat...
Forum Discussion
For 2011, it turns out there is a rear axle difference. The F250 only has a 6200# rear axle (yes, the axle it rated at that, independent from the springs). The F350 gets a 7250# rear axle. Both are Sterling 10.5" axles.
https://www.fleet.ford.com/truckbbas/topics/2011/2011_SD_Pickup_specs.pdf
OTOH, the 2015 F-series share a lot more.
https://www.fleet.ford.com/truckbbas/topics/2015/15_SD_Pickups_SB_Updates.pdf
For the most part, the 2015 250's and 350s are the same, except there a few configurations where the rear spring rate may not be the same. Frame, axles, brakes, etc all are identical.
https://www.fleet.ford.com/truckbbas/topics/2011/2011_SD_Pickup_specs.pdf
OTOH, the 2015 F-series share a lot more.
https://www.fleet.ford.com/truckbbas/topics/2015/15_SD_Pickups_SB_Updates.pdf
For the most part, the 2015 250's and 350s are the same, except there a few configurations where the rear spring rate may not be the same. Frame, axles, brakes, etc all are identical.
