Here's the history on this:
most recent idler arm diagnosis from this shop was when I just bought two new tires, not during an alignment.

I knew it wasn't the idler arm, because they gave me the same diagnosis a year ago
when they did do an alignment. So I replaced the idler arm myself.
They came to this conclusion by twisting the passenger wheel back & forth
when the car was off the ground.

Doing some checking with my son tonight I think it is play in the steering box.
With the front end off the ground, twisting the RF tire makes the LF tire twist.
While holding the LF tire tight the RF tire has no play.
While holding the steering wheel tight to one side the RF has no play.

There is no play in the sway bar when twisting the RF tire, so my original
suspicion was wrong, too.

The shop misdiagnosed the idler arm and also missed the bad bushing
because that clunk was there when I had the alignment a year ago.
On other work they have been honest and reliable and they have a very
good reputation locally. I think it comes down to an individual worker.

The shop is Radial Tire in Sacramento. I'll call them and let them know
about their bad call and will look for another shop for the next alignment.

Getting back to the original problem, here's a photo of the bad, practically
non-existent sway bar bushing.

Jeff

Attached Thumbnails

 

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1984 300SD 300,000 miles--two tank WVO setup
2.88 diff & 500SEL anti-squat rear end