Ok i just checked and a watts center-outlet kitchen sink drain will barely work......it measures 6.5" and you can cheat that alittle to get your 6 3/8". I promise it will work.....just sat it down in the shop!This is from a suburban Chicago home. Built in the 1950's. It's a center outlet drain for a laundry tub. It's about 6 3/8" on center. Come on, Ron and KTS.