For those looking to build their own upper/lower arms, spindles or links Camburg Engineering has what you're looking for. Camburg Engineering CNC machines their uniball cups in-house from US 4130 chromoly, not cheap mild steel or imported materials. Unlike most other companies they also machine the OD of the cup to remove the material scale/finish for better welding. Don't pay more for something less. Camburg designed their cups for maximum mis-alignment and strength. These can be MIG or TIG welded and also heat-treated after final fabrication.