Another likely clueless question:

I'm intending only to replace the upper shock mount, not the whole shock absorber. But I'm assuming I should mimic shock replacement procedure to be sure there are no up- or down- pressures on the shock absorber when I remove the upper shock mount.

I have supported the rear of the car (L side) with a jackstand under the trailing arm, just forward of the lower shock mounting nut. Image at:

https://www.brickboard.com/IMAGELIB/volvopic.htm?js_link=&id=14107

Note the trolley jack in the background under the trailing arm bracket just forward of the trailing arm bushing. I've released and then reset its hydraulics, so taken most of the weight off it.

Haynes says to raise the rear of the vehicle, support it on jackstands, and then put a floor jack under the spring pan and take the load off the shock absorber.

But it seems like this jackstand does support the spring pan, essentially, considering its position. It's under the trailing arm, which is rigidly attached (i.e., part of) the spring pan. Maybe I'm missing something.

Maybe I should re-lift the car with the trolley jack (basically at the underbody?), and then put another jack under the spring pan?