Actually, that lower control arm started in 1962. The first sway bar LCA's started in 1965 and was the same in '66. The tabs were slightly different than the '67-72 version, but, they do interchange and will work with the factory bars in their respective years. If the OP is going to use an aftermarket sway bar with his '71 K-member in this swap, I would probably use a LCA without any tabs, unless you can find an aftermarket one that uses the factory tabs. Find the sway bar you wish to use and see what the manufacturer recommends or requires.