Hi,
Pro-Touring F-Body Sub Frame Connectors can be both bolted or welded or a combination (weld to the unibody/bolt to the subframe).
They require no floor mods and have almost no impact on ground clearance. There are a few brands out there, be sure to choose a brand that joins the subframe to the rear rails...not to the spring mount bolts. Other brands like DSE (Detroit Speed and Equipment) are "weld only" and require cutting the floor pans to fit.
Here are some pics of the PTFB connectors fitted on my project -
These are $299 plus shipping, or can be picked up at Ingleburn. I have one set in stock at the moment....there are a few more sets on order, but they surface ship so can take 8-10 weeks to show up.
Easy to fit, drilling the holes can be a little awkward on the rear rail, but not too bad. The connectors themselves fit very nicely.
You can call me on 0417680623 if you'd like to discuss these parts, or any other pieces you find on the website at
http://www.pro-touringf-body.com/NOTE - the manufacturer recommends solid body mounts when welding these connectors in - or polyurethane or solid mounts when bolting them in. You can see the solid mounts in one of my pics.