I've done some checking and some aftermarket companies are using upper ball joints in the lower control arms. This is a misuse of parts according to the NSRA Safety Division. When I contacted Heidts,(I have their control arms in my '51 Chevy Bel Aire) they wouldn't tell me why they are using upper ball joints in the lower arms. They said they have been doing that for years. That still doesn't assure me that it is a safe application.
