Damn! Torque Boxes Cracked.......

That metal looks really thin, thinner than the rest around it. It wasn't rusting from the inside was it? We are doing sheet metal at work on a 66 coupe and i had to do the torque boxes today, this thing was paper thin. Looks like all you need is a good MIG welder, drill the ends, and get reinforcing plates. Now im worried about my torque boxes.
 
Sorry to hijack.

While working on the stang this winter I noticed I have a small crack on each of my TB as well. Plan on getting them fixed in the spring when I have subframe connectors/battleboxes welded in.

Anyway I was back there cause I was looking for the source of a clunk I get under load, shifting hard, or going over a rough road. Could this be related? Is this the symptom of a bad suspension component. What else should I do/check to keep this from getting worse or returning after repair.

Also the LCA bushings have alot of red grease around them, its caked on. I assume that this means they went bad?