cupping or chipping on the rear tires

[dlphnfn]

I've been doing some searches on what is causing cupping on my rear tires.

From this site it looks like it's from worn rear suspension parts.
Where can I get this part Ford calls a tie rod on the cheap? (part #5)

Tousley wants $75 for the "tie rod" and another $15 for the bushing. That's $165 for something that i would think RockAuto would have for far less for a product at least as good (Moog), but I can't find them.
Has anyone else experienced this cupping on the rears and resolved it with certain parts?
Thanks,
Erick --

 

[zorrex]

I think that's the trailing arm. I don't believe you can get the trailing arm from RockAuto, but you can get the trailing arm bushing, which is probably what has failed anyways...

 

[dlphnfn]

How are the bushings to replace? Do I have to get it done or can a home mechanic, DIY'er do it?
Erick --

 

[zorrex]

I'm not quite sure, as I've never done it. Sorry

 

[BrApple]

I don't recall which bushing it was but some in the rear suspension are suppose to be "soft" as its for the passive rear steering.

 

[mcgarvey]

The trailing arm bushing that wears out is in the knuckle, not the trailing arm itself. Rockauto has them.