Our shower was put in in 1978 by my grandfather who was a plumber by trade. He installed a 36x36 durastall shower. We HAVE to replace this shower after 34 years. My question, the shower drain is 18" center, I want to replace the shower with a 36x48 tile shower but my husband says there is no way we can move the drain. Is there a way to do this without moving the drain?