Subframe connectors

These cars can flex. I've heard of doors not being able to open when up on a 2 post lift.

US Car Tool Frame Connector Instructions.

Hint #2. Do not weld your car with the frame supported on jack stands and the tires
hanging in mid air. Support the car on the suspension (under the rear axle tube and front
lower control arms is a good spot for Mopars) so it is “loaded” and have the doors closed
while you weld the frame connectors in.

https://store.uscartool.com/assets/...Frame Connector Installation Instructions.pdf