Ah, now I remember your mod; way better than a panhard. Can the rear axle still pivot some on the rose joint on the diff?
Edit: There was a video going around a few years ago of a racer with a panhard rod Healey who'd put a GoPro in his axle well as he did some laps. It was pretty scary how the axle bounced around, fore and aft almost as much as up and down.