On a GMT400 K vehicle, often by the time the upper ball joints are bad...the upper control arm bushings have been wiped-out for quite a while. Thus the popularity of simply replacing the entire upper arms--gets you new bushings and new ball joints.
Lower control arm bushings should be inspected. They do seem to last longer than the uppers, but clearly they don't last forever. Lower arms are harder (or impossible) to find. There's some folks claiming that Astro Van lower arms are interchangeable with GMT400, and others that say they're similar but different. I haven't compared them, and GMT400 lower arms are not available, I guess.
I have no idea what's available for C trucks.
Seems like they're the preferred ball joints now.
I used Moog. Maybe I'll regret that.
The LCA's are available for all the C trucks, I guess it's the K trucks having trouble finding them. Can't speak to that.
I found the opposite on control arm bushing wear recently, though. My uppers are crusty and cracked for sure at 160K+ miles but appear intact; the lowers have actually failed and let the arms shift.
Having done a full "replace all the parts" front end rebuild many years ago on another truck, I just bought loaded arms this time. I'm sure I made more work for myself in the past by doing poly bushings instead of OEM rubber, dunno, but the bushings were not fun.
For this current project I went with Moog; they
used to be a trustworthy name, hope they still are.
Spareparts - as far as using past performance of your OEM stuff, you can't compare today's offerings and expect the same quality and service life. They aren't the same parts from 30 years ago.
I'll say at 150-200K miles your ball joints might seem fine but you should really test them to be sure. Frame supported on jack stands, long lever (long pipe, length of 4x4, etc.) prying upwards on the tire, have a helper do this while you watch the ball joints for any slack.
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Richard
