I pulled an original tub that was installed in 1971. The drain assembly kit just slid into the 1 1/2" pvc pipe that leads to the sewer pipe. Shouldn't this be connected? Should I add one of those threaded nuts that are used for sinks. It is a compression fitting. The other option would be to permanently secure it with glue, but that would seem like more trouble if I need to remove something.
It is a slab foundation. There is a small square cut out around the pipe. Should I fill it back in with concrete or just leave it like that?