I currently have a 42"x60" shower stall that needs a new tile floor. It is built on a concrete slab. Since we are going to have the remove the shower pan down to the concrete slab we want to put in a whirlpool tub instead. The shower stall has a center drain. We want to install a tub with a left side drain. How is the easiest way to accomplish moving the drain from center to left. Also what is the difference between the shower drain and a tub drain. Everything is pvc, I know that the shower drain is bigger than a tub drain so I will have to have a reducer. I guess the big question is the drain location since it is on a concrete slab. I have been thinking of two appoaches. First would be to cut open the concrete floor and move the drain. The second would be to build a platform for the but to sit on and run a connecting pipe from the left side tub drain the the existing shower drain. I know I need a trap for the tub drain. I am not sure if the shower drain already has a trap (how can I tell?). Also venting, how can I tell if the current shower drain is vented? Sorry for the long post. Thank for any help anyone can give.