Dangerous situation, need some help please

[Flatpat]

I have a 1978 K30 Crew Cab that I have been getting back on the road. I'm having an issue where if I take a fairly sharp turn at a little bit of speed (15-25mph), the truck will start a very violent wabble, like the tires are going to fall off. If I slow down to a crawl it stops and then I can continue on and it rides great. It doesn't do it on slower turns or the sweeping highway turns and so far it's only done it on right turns. I made sure all the wheels are on correct and the lugs are torqued down. The tires are radials and in pretty good shape. Figured it wasn't a tire since it straightens out. Best I can tell everything is connected throughout the suspension and nothing appears broken. Any ideas? It's pretty scary.


Thanks,
Patrick