Yes, the spindles are longer. Not sure how long, but Ive been told they are shorter than other free-spin kits.
Considering the OEM locking hubs are actually recessed within the wheels, Im not concerned at all about anything a bit longer.
My junk is all 1480. Far as I know, the 1550 joints and shafts were exclusive to the F450/550 They are considered an upgrade for the 2005-2014 250/350
If the 1550 ever made it to the 250/350, it may very well be a 2014/2015 change.
The 2015 to present kit is here...
The original Dynatrac™ Free-Spin™ Heavy Duty Hub Conversion Kits are popular with off-road enthusiast as well as companies who rely on their Ford trucks for work. Free-Spin kits replace problematic unit bearings, eliminating a weak link that is prone to failure.
www.dynatrac.com
And hubs, there is ZERO reason to buy a complete timken hub once you go this route.
If all you want to do it change hubs, you stick with unit bearings.
The rest of us that prefer serviceable bearings, we just buy bearings & races.
Those are less than $30 per side. And again, thats assuming you ever have to actually change the bearings.
One of the biggest issues with unit bearings is that if/when the unit becomes contaminated, like with water intrusion, you are SOL.
With serviceable bearings, not the case. Pull them out, flush them clean, inspect, repack, reinstall.
All you are out is a bit of time and grease. And seals if you are doing it "properly"
Do this as a preventative measure, and the bearing will quite literally last the life of the truck.