Finally got my lift-off oversteer back. The 50 year old straps had pretty well disintegrated during the Gambler 500 last year, but I finally had some time to do maintenance around the Saab, and swapped in a new set. Gave the shock bushings back there a blast of silicone spray to keep them quiet too. Yes the rod and lever back there belong to an Armstrong lever shock.
Since the limit straps had failed, this meant the rear axle dropped way down when the back of the car was jacked up. So I had to jack up the car, remove the wheel, replace the strap, put another jack under the axle to get it high enough to get the wheel back on, lower both jacks, and then maneuver the strap back under the spring perch on the axle. But hey, it works now and the car rolls less and oversteers on command (or if you enter a corner stupidly fast accidentally).