Further information: here are the resulting alignment readings from my last trip to the shop.
Camber left (-0.33deg), Right (-0.30deg),
Cross camber (-0.04deg)
Caster Left (9.84 deg) right (10.43deg)
Cross caster (-0.59deg)
toe left (0.19deg), right (0.26deg)
total toe (0.45deg)

This is with the passenger side reaction ball joint all the way to it's limit. Any insight? Thanks!

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1989 560SEL (172k)
1989 325IC (122K)
2004 Suzuki Volusia LE (3500 miles)
2005 Yamaha Road Star (20 K miles)