Which is better? Coils or Leaves?

This is a difficult one to answer. Ultimately, whichever is more easily installed will give the owner the most bang for the buck. If you're the owner of a 80-91 truck that can easily be adapted to coils or leaves, you have some decisions to make. Both suspensions are capable of great flex. Both are reasonably durable. Coil suspensions can be built to have better approach angles, while leaf springs are more easily installed and tuned.

I found a king pin D60 and a ball joint D60. Which is better?

The earlier king pin-style axle is prefered by wheelers for its easy adaptablity to hi-steer conversions. It is also believed to be slightly stronger and more durable. However, if you aren't bothered by the difficulty of steering conversions, the cost and condition of the axle should be the driving factor in choosing.

What about this Chevy 60 I have sitting around?

Ford trucks are largely unique in using driver's side differentials on their front axles. Chevy and Dodge use passenger side diffs, which will require at least a new transfer case to work under a Bronco. 95+ model Dodges use a coil-spring, 5-link, driver's side diff. However, these axles are not preferred because of their small-diameter, low-spline axles.

That said, the purpose of this FAQ is putting a FORD D60 under a FORD Bronco. You're free to put a Chevy under your rig. It can be done, but this paper isn't going to tell you how.

I found an axle out of a dually F-350, but it has weird hubs. Can I still use it?

If you find a dually F-350 axle for cheap, you can swap the hubs to single rear wheel parts using F-250 TTB Dana 50 hubs.