My searches show it has independent rear suspension which introduced a ton of variables.
If the bushings are worn the suspension geometry can go all over the place.
I had a 63 Econoline van as a kid
The tierods (solid front axle) were worn out.
If you hit a bump at the right speed the front of the van would death wobble as in each tire going toe in then toe out in rapid session. the only way to stop it would be to jab the brake, loading up the front suspension momentarily. That caused both front tires to track together again.
