I'm reading through the W126 idler arm removal and replacement process. The last step is "check balljoint and adjust if required (40-320)." 40-320 is the front wheel alignment job. Does this last step mean to check the general wheel alignment after replacing the idler arm bushings, or is there a ball joint local to the idler arm that needs checking?

Is the idler arm keyed to the big bolt that goes through the idler arm bushing? Is there a position to note when taking off the idler arm?

Thanks,
Sixto
91 300SE