I had 1999 F450 with Dana 80.
The door sticker was 15k, while I had it at over 20k quite few times.
Some interest when you load steam roller on pickup truck
Anyway, my F350 is having stronger suspension than older F450
Probably partly due new trucks build stronger, partly due that my truck was sold as extended wheelbase chassis.
Bottom line, even in the same year those trucks come with different suspensions, so good luck doing your homework.
Last time I check, diesel F350 were coming with $70K price tag?
Additionally, my observations is that till F450 trucks are build as grocery getter with short wheelbase, unless you get special order.
I had constant problem on F450 with weight distribution.
Short forklift at 10,000 lb was fine with counterweight behind the cabin, but 6000lb tractor would have center of gravity behind the axle and even air helper bags would not be enough for rear sag.
You want to get truck design for heavy weight, you need to go F550.
