Pretty big assumption you’re making there. The rust in the rear rails probably isn’t causing the driving issue, but there’s nothing that says that the front rails can’t be as rusty as the rear rails are. And if there’s rust in the front rails in the usual places, like right at the UCA mounts where dirt likes to collect, it could easily be causing the issue.
Looking for rust just goes along with inspecting for worn out bushings, broken LCA pivot tubes and cracks in the steering mount at the K frame. And of course the alignment, since a lack of positive caster can make the car feel like steering a shopping cart.
