subframe connectors

Can you build the bolt in version? I am gone for a couple of weeks but will look into a set of weld-in for a 66 barracuda and would like to know if you can do bolt-ins for a 69 dart. I have never watched an installation, but wonder about the fire hazard with undercoating, carpet etc... Thanks!

Any time you weld you'll have a degree of risk. Welders set their pant legs on fire, etc.. Point being you cant reach zero risk. Some types of weld splatter much less than others.
As for subframe connectors.. The type that bolt in can be welded where they are bolted which reduces risk of carpet melting and such.