Originally Posted by b. rock
2016 knuckles? Spyntec hubs? I'd love to add a truetrac or similar to the front but that's not quite in the budget at the moment.
As you've likely already learned, it's a slippery slope... but since I'm spending your money
-Figure out your steering geometry now, decide on high steer or not, figure out your track bar and steering damper strategy, so if you need to fab and weld, you do it on the bench
-Big brakes w/new parts (if bigger is an option, if not, than just new pads, caliper, hoses and rotors)
-Sort out the speed sensor compatibility between your new axle and your van (there's often more to it than meets the eye)
-Best quality replacement ball joints
-Manual locking hub conversion (If the used axle doesn't already have that)
-Ring and pinion ratio that you want (now is the time to add a locker if you can afford it), figure out what driveshaft you'll use, make sure you have the correct yoke before setting up the pinion bearing crush. Internal axle work is easier to do now
-New seals, bushings, axle u-joints, stub axle bearings, new brake calipers
-Better hubs (than stock unit bearing) if planning on larger tires and wheels
I'm not sure where the cutoff is for the larger ball joints (than the 2001's), but if the '13 inner C and knuckles take the larger ball joint, use the best ones you can get, if '16 knuckles take the large BJ, then I'd do that. bigger front bakes too, F450 maybe (but you need a 17" or larger wheel I think).
I'm not sure what Dana Engineers were thinking with the unit bearing deal, both inner and outter bearings are almost right next to each other. As if the 4x4 customer isn't going to upgrade the tire and wheel package? I digress... If you plan to move the wheel center outward, (from stock F truck) or put on larger tires and wheels, look at doing the Spyntec upgrade. The non-servicable unit bearing deals are junk. If your budget won't allow the pricey Spyntec route, then go with Timken units. Ditch the vacuum engagement locking hub set up, and convert to manual hubs, but you want to decide on bearing units before you order Warn manual hubs, I'm pretty sure Spyntec takes their own hubs, they are a different design than unit bearing Dana.
Then there's a 1/4: thick steel diff cover, and 1-1/4" tie rod w/Chevy tie rod ends, better shock mounts to accept longer shocks, different bump stops, differential vent hose set up....