7 1/4 SureGrip for 1966 Valiant Resto

I am looking for a serviceable or rebuildable 7.25 Sure Grip third member. Have a perfectly good onelegger that would like to make posi....anybody got a solution?
Have new small bolt paytern wheels and tires that came with car and prefer to keep them and just need to convert the existing setup to sure-grip if possible? Thanks...I will pay to ship or pickup in Northern California....Thanks