If you find the bolt rusted to the sleeve you might try what worked for me.

That sleeve is a piece of rolled steel. That means it will have a seam in it. The rubber on the bottom end of the shock will hide what you need to see so the rubber has to go.

I removed the rubber by burning it out with a propane torch. You have to be careful!! Have your fire extinguisher and/or water in place before you start.

After the rubber is gone you will be able to move the bottom end of the shock some and expose more of that rolled sleeve. Rotate the bolt until you locate the seam. Use a nice sharp chisel on the seam line and give a few sharp cracks with a hammer. Repeat on the other end of the sleeve. That should break the bond between the sleeve and bolt.

Don't beat on the thread end of the bolt. Install the nut so that your hammer is hitting both the end of the bolt and the nut evenly and you should be able to reuse the nut and bolt- the sleeve is part of the shock.

Good luck,
Randy

Illustrating Ted's point:






--
Art Benstein near Baltimore

A jumper cable walks into a bar. The bartender says, "I'll serve you, but don't start anything."

you have very few options to get it loose.

1. vise grip might work but i doubt it
2. an acetylene torch to heat the crap out of the sleeve and then use vise grips might work
3. mostly likely you will have to angle grind through the sleeve/bolt and remove then finding another bolt and sleeve

"I can't get the lower bolt out of the rear swing-arm so I can remove the rear shock."

Either have the body supported on stands and raise/lower the axle/trailing arm. Or have the axle on stands and raise lower the body. Remember that you are likely working under the car so make sure the weight is properly supported.

First remove the upper part of the shock by removing the nut and pulling off .

The lower bolt may give trouble during removal because it may be seized to the spacer sleeve it is inserted in. You could try gripping the sleeve with vise grips while turning the bolt.
--
1980 245 Canadian B21A with SU carb, M46 trans, 3:31 dif, in Brampton, Ont.

Thanks for the response.

I've got a jack under the swing arm but I don't know how much to jack it up to equalize the tension.

Should I tap on the bolt as I jack to find the sweet spot?

You need to put a jack under the rear part of the trailing arm to take the pressure off the extended shock. Once you do that the bolt will be easy to remove.
Dan