what do you make of this?

yeap,looking like a tar has melted, dripped from the floor plug versus a weld. Now it makes me wonder what other issues are to be found? Interior has been sprayed. (was the famous burg color), but does have a 340,727,8-3/4.
i will post up some of the car tomorrow. Car has been re-quartered, some rear floor holes, trunk well replaced.