[Paul R.]

No, this is a “pin”.

I don’t have an exact image, but, at this point, I believe it is a “hex head”: visualize a bolt head with immediate threads, and then a “smooth” pin that goes on through a boot and into the caliper body, ending inside the body. No nut to split.

What bugs me is that if the only threads are just “under” the hex head, 3 days of PB Blaster should have some effect. It may not be the “best”, but in the past I’ve found it to be fairly effective. I may try the acetone + ATF next...

[kitchen]

Steel bolt threaded into aluminum? You have 2 issues to overcome. A high probability of (1) galling, i.e., fusing of aluminum on the steel bolt during assembly; and (2) galvanic corrosion. Either can be a nightmare. Depending on the extent of either, the dis-assembly torque may exceed the strength of the bolt. Those bolts probably have a low torque spec, guessing 20 something ft/lbs. Try setting your torque wrench a few ft/lbs higher to break the bond. Multiple cycles of heat and penetrating solution, milling or grinding a socket to get full purchase, and patience.

I'm not familiar with FoMoCo parts ... is it SAE or metric (we know it's not Whitworth :) .) I've got hex, star, and triple square, so make sure the crud and corrosion on the bolt head doesn't mask something.

Depending on your personality and wallet you're probably better off trading the calipers in on a remanufactured fully loaded set.