Hey everyone, I am new here to the forums, spent some time on the F150 forums but I'm looking to sell the old girl and upgrade to a '99-'2000 Super Duty (no powdered metal rods). Really nice Crew Cab F350 Duallys are easy to come by in my area around 10k for those model years. After doing research I was throwing the idea of junkyarding for the 550 Dana axles and other suspension parts, but I could never find a solid answer as to whether the 550 frame is any bigger or better built than the 350. Anybody have any idea? Thank you


Tl;dr Are F-550 frames any different than F-350 frames from 99-2000 model year?

 

The chassis cabs are completely different than pickups. The F550 uses standard straight C channel for the rear frame section.

 

Hang on, I'll summon @Y2KW57 ...he'll tell you.

 

TL;dr: Yes. Very different.

The F-350 PickUp frame rails (all cab lengths, all bed lengths, all wheelbases, all drive configurations, any number of tires whether SRW or DRW) are thinner in material thickness, shallower in web height, narrower in top and bottom horizontal flange width, wider in vertical web spacing rail to rail, different in crossmember location and shape, weaker in section modules and resistance to bending moments, and not formed to accommodate the mounting locations of the spring hangers, anti sway bars, and shocks of a Dana S135 axle from a Ford F-550 of that era.

The F-550 chassis cab frame rails (all cab lengths, all wheelbases, all drive configurations) are significantly thicker in material thickness (up to over a half inch thick in some sections on L reinforced frames), taller in web height at the forward rear spring hanger, wider in top and bottom horizontal flange width throughout the frame rail, narrower in vertical web spacing rail to rail aft of cab, different in crossmember location and shape, significantly stiffer in section modules and resistance to bending moments, and formed to accommodate the mounting locations of the cast spring hangers which mount on the frame in two planes, and has cut outs for the shocks of the Dana S135 axle housing specified by and for Ford at that time.

 

You for the in depth reply man. Appreciate the help.