If the sway bar broke, you should clearly see it in two pieces. I agree we could use some pictures.
Steel that rusts, usually gets larger since rust is some multiple times more volume than the steel started out. If your bar is smaller, then I suspect it was smaller from the factory. IIRC, there were at least options for 19mm and 23mm.
If that is the case, and you know of some larger at a junkyard, I'd go ahead and pull a larger one from a junkyard for better sway control, along with the bushings and mounts, though I would just get the bushings for the heck of it and get some new energy suspension poly bushings instead, or hunt down the ford part # for rubber ones if you don't want to have to lube them periodically to keep them from squeaking.
Anyway, those bolts are surprisingly durable, try letting some penetrant soak in for a few hours before trying to remove them.
If they do break off, you could try extracting them or drilling them out, or "maybe" just drill new holes near the old ones and use a hardened bolt, nut, lock washer or lock nut from the local hardware store. I don't recall the original size, it's probably metric but a standard would work if you don't mind remembering that you've changed it.
I'm trying to remember, does the bar bolt to a plate on the axle? If so there is the option to use a U-bolt around the whole axle, similar to the ones holding the spring seats/shock absorber lower mounts on. They're around $6 ea. at Rock Auto. The axle is 3-1/4" diameter and they'd probably need to be about 6" long but I'd measure it to be sure.
Maybe it's a lot easier than I'm making it out to be. I'd first soak them in penetrant and see if they'll come off.
Edit: Maybe I was way off, re-reading your post I realize you wrote about the link bolts to the frame, or did you mean the bar bracket bolts to the axle?
