That's a new one - frozen shock bolt

Was replacing the rear shocks on my new-to-me Mazda5, since the driver's side was blown out.  Soaked all the bolts/nuts in PB Blaster for a few hours.  Got the driver's side done, and switched over to the passenger side.  Removing the lower bolt, and after it came out 1/4" or so, it froze up.  Hard.  My cordless impact that can loosen damn near anything just stopped turning it.  Here's the part that's weird - it can't put it back in, either.  I tried loosening or tightening it with a breaker bar, too, and no luck.  I'm guessing rust has it frozen in place, but I've never seen it where a bolt came out partially, got stuck, and couldn't be re-tightened.  For now, I soaked it all in Kroil, and am going to reassemble it so I can get it off the jack stands.

Any non-destructive ideas for dealing with this?  My first plan is to let the Kroil soak in for a few days, since I don't need to take the car anywhere.  I figure I'll get the propane torch out if I have too, but I am afraid of cutting the shock bushing/bolt out, since then I'll still have to figure out how to unthread the rest of the bolt. 

On my Saab C900 the rear shock bolts were both frozen solid. Big impact did nothing. I tried penetrating oil, heat, both in combination, and CRC Freeze-Off, all to no avail. Ended up having to cut them off, which was less than fun, as access inside the trailing arm on the C900 is poor at best.

Happens all the time if you start to graunch it out and it stalls.  You galled up a little ball of something and it seized.  Much cursing ensues.

The trick (for the future) is to run it back iuntil it stops and run it back in again RIGHT AWAY instead of ripping it loose until it stops and then trying to loosen it harder,  Unfortunately there's no good way for me to describe the feel you get when it binds up to the point it can't move, vs. only binding a little and you can keep reefing it loose.

Heat, like red hot.

If its a thru bolt, air chisel on the end and drive it out.  Replace with new hardware.  

If its into a blind threaded hole, heat may work but dont be surprised if you snap it off or pull the threads out with the bolt.  

Either way you should really just replace the bolt at this point, so game on for destructive removal. I like a cutoff wheel on an angle grinder.

Problem with red hot heat is you ruin the heat treat. Now, if there's enough factor of safety that a weakened bolt can hold it is debatable, but it will be weakened.

It’s a through bolt, but it is still fully threaded, so air hammer is not an option. Frankly, I’m not 100% certain it’s it stuck in the threads, or to the shock bushing, but I strongly suspect it’s the threads, since the rubber part of the bushing isn’t mangled.

No matter how it comes out, I intend to replace the bolt.  I’m just hoping to not have to get too destructive.  There’s just not a lot of room to work with there, so if I can get away without cutting or a lot of heat, I’d prefer that.  Also, if it is stuck in the threads, cutting the bolt head does not seem like a wise idea.  I think I’ve still got some MAPP gas, but I definitely have propane.

Similar thing happened to me with a rusty Miata. After wasting hours over a course of days trying to do various things, I bought a used control arm for $20. It was reinstalled in minutes. 
Junked the shock and LCA. 

In reply to eastsideTim :

You want MAPP.  Get the bugger orange.  You can barely do that with MAPP and propane will only get you bored.

Guess I’ll be hitting it with Kroil whenever I’m working in the garage for the next few days.  I’m not using a torch (or any other destructive method) until the replacement bolt has arrived.  Then, I’ll see f I can get it loose without heat first.

I've been able to free some seriously stuck shock and alignment bolts by rocking them back and forth with an impact. Go tighten-loosen-tighten back and forth for a long time. Coupled with a generous dose of penetrant it really works. I got it from a YouTube video somewhere years ago and it's saved my bacon a few times. 

Tried again with the breaker bar and the impact, but no luck, so I pulled out the MAPP gas torch.  After a couple minutes of heating it up, the impact wrench was able to zing it right off.  Bolt doesn't actually look to bad, but since I have a new one, I'll use it.  Just waiting for everything to cool back down first.

Also wondering why a lower shock bolt needs to be fine thread, especially one in double shear.