You're probably right about the dealer being best in this situation. I'm too susceptible to suggestions -- I've noticed this in other situations too -- like this one guy I've never met on a web page I've never heard of who thinks dealers are a bad idea.
Which is the radius rod?
Is that the same as the rear lower control arm, the locating arm, the rear lower suspension arm #1 (I think that's what the shop manual calls it)? I think it has other names too. Makes it hard to shop for it.