Sorry, but I must be more blind than I thought - I read and re-read and I'm not seeing anything about a grounding pigtail in your post. Anyway, I do see the clips that must allow the lower 3 mounting points on the cluster to ground. The alternator speed nuts had been replaced previously with normal nuts, though I did notice that the ground side was finger tight.
That said, I think I found the problem. One of the pins got bent during my last install (I've been through this about 5 times). I'll have to dig up that article you mention about repairing them. It's hanging by about 1/3 of the material on one side, so if I stand it up, it stays in place until it gets some pressure on it. I swear, if it isn't one thing, it's another. I felt great about getting the steering box in there and getting the car back on the road, and getting the speedo repaired, and now I've broken part of the cluster. :/
