I kind of looked into car spindles since there are drop spindles available. I have seen some dwgs made by some folks comparing the different body spindles and there are many differences. I believe the closest ones are from “C” bodies and there are a few variations of those. A few “C” body guys were looking to use them but the drop spindles available are a single casting for late A, B, E, F, M, J, R bodies as noted. The ball joints are smaller and no one I could find had used them successfully.