Sub frame connectors

I disagree. I've done US Car Tool stiffeners both ways rotisserie and on a hoist. The only trouble is getting undercoating off or not knowing how to remove it. Other than that it's just welding. The trouble area on sub frame connectors is not placing the weld on the US Car Tool sub frame connector and rolling the weld into the floor pan. Once you learn that, it's easy. Just takes time and a good welding jacket.