As it turns out, removing the rear springs to replace the bushings was more intuitive than I thought. Following the manual and some great guidance from a VTCI member, it was straightforward—if sometimes heavy—work.
I ran a die down each leg of the U-bolts to chase and clean up the threads, which were pretty beat up after years of road debris. I also tapped out two of the nuts, which were damaged when I unscrewed them. I’m told that wasn’t such a great idea, as they are meant to work like pinch nuts, locking in place. I’ll check the torque on them after a few hundred miles, just to make sure replacements aren’t in order.
It’s hard to say for sure, but wear marks on top of the axle lead me to believe that the clunking noise was coming from the U-bolts walking around the axle over bumpy stretches (the rubber insulators having degraded and shrunk so badly.) If the new bushings don’t quiet things down, the next step would be to replace the springs and mounting pads. For the moment, though, except for replacing lock washers, I reused all the non-rubber parts. Despite some rust and corrosion, everything still appeared sound, and the ride height is ok.
I don’t yet know how the new bushings feel because the new fuel pump is not yet installed. I discovered that with the car up on jacks, tires hanging, the anti-sway bar in front interferes with its removal. (Having the car up in the air did make an oil change super easy, though). The pump came right out when the bird landed. With luck, I’ll have everything buttoned up in a day or two.