When my house was built Mansfield Stop and Waste Valves were used for the outside and under sink shutoffs. Several years ago I had a packing nut leak and was unsuccessful trying to repack it. I couldn't find another Mansfield valve so I bought another brand and used it's stem unit in the Mansfield body and it worked. I had been told that different manufacturers built to different specs and this might not work. I have another valve that is leaking and have not been successful trying to repack it. I can't find the the same brand that I used last time and am wondering if a different brand might work or I was just lucky. Are the body threads different in different brands or is the threading consistent? Is trial and error the way to proceed with fingers crossed?