There was a bunch of tar paper-type sound deadening stuck to the floor. Let the dry ice sit on it for twenty minutes or so, hit it with a hammer and it shatters into chunks you can pick up. Otherwise you're chipping it out with a chisel. Saved 15 lbs or so taking it out.

Hi Chuck33079 - Thanks for the pics re: track car build - is that dry ice I see on the floor in some of the pics - what's going on there?