Subframe connectors?

Make sure the car is not on stands when you put the subframes in (especially if you are welding them against the floor. Having it sitting on all four tires is a must to reduce the chances of body flex when you take it off the stands.

It's okay for the rear end to be on stands, since this mimics the car sitting on the ground, but the front end needs to be sitting as it would on the ground as well.

I used the Mopar Performance ones and they fit great, but they're fairly pricey. There is a member here who makes them much cheaper, and I'd use those if I had to do it again.