Thanks... It done now, it already has a brass valve, but not a full port. Due to clogging, it became a all day chore. I think I will order this https://www.amazon.com/Rheem-AP12231B-1-Drain-Valve-Brass/dp/B009AXO2AM/ref=cm_cr_arp_d_product_top?ie=UTF8
and do another flush in the spring, or...