I just bought the entire links (with the necessary bushings) for my stock explorer as a kit. They should come as a set all ready to "plug and play" so to say.
But if you have a modified suspension and can't just order the standard part, then you could just do this.
The sway bar links just need to have the correct dimensions to fit when the truck is standing on completely level ground (especially not leaning to one side!)
So you can just crawl under the front and take the measurements for the length when the truck is standing on level ground and that should pretty much do. If necessary you could get the diameter of the bushings on a standard set.
They look similar to like this:
Advance Auto Parts - Down for Maintenance (This in the link is not the correct part!!! I just linked it because of the picture.)
The dimensions are really not very critical.
And whatever you install, don't tighten them too much when you install them, or they will only wear out quick.