[Tx Firefighter]

I coat a bunch of trailing arms. Before you can answer the question though, you must know what type of bushings the customer is planning to run. If OEM rubber type, the shell needs to be removed. If urethane, the shell is left in place. Regardless, I always mask the inner surface of either the arm or the shell to make sure the powder buildup doesn't interfere with the bushing fitment. Make sure your guy does this too.