The spring pivots have rubber bushings, which makes welding them properly almost impossible. Cut the pivots off the housing and replace them with spring mounts for a later model rear axle. Most of the race car equipment vendors like JEGS or Summit have them. Yes, the center section is a bolt-in fit, but that's only part of the conversion. I'd suggest building a 4 link system so you can adjust the pinion angle for the best performance and the least vibration instead of going to a rigid spring mount.
Jerry

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