I had one in my '08 2500 a while back. The tie rod ends, pitman arm, and the ball joints were worn out at about 135k. Remember a while back when we had a thread about the pickup that was hanging by it's trailer hitch off of a bridge in so. Idaho? My shimmy started on the same bridge although in the other direction. I'd slowed to about 60 as I was towing a light utility trailer but when I hit that bump, it got lively. It quit when I got down to about 50. They hadn't given me any hint of being worn until then.
Back in the 70's and before, this was common. I'd experienced it quite a few times growing up. Modern cars are much better built and now it's almost a rarity in comparison.
Same truck as mine but mine made it to 139k last summer. No prior notice and when leaving camp and got up to about 55 all hell broke loose, I was about sideways before I could get it somewhat under control. Eased it to a friends garage and he ended up replacing everything it in the frontend, no problem since. He told me it had a lot to do with me having a plow which is almost 1000 pounds and is on the truck from Dec-March.
