Eastman Speedflex stop valve nut replacement
I have a mid-80s Eastman Speedflex valve that is leaking any time I look wrong at it. Replaced all washers but the nut is probably stripped, I can't tighten it down it skips the thread and gets lose. It's just above cabinet floor and is connected to dishwasher intake, the pipe is going up another six inches and there's a second valve that's connected to the faucet, and then there's another foot or so of capped pipe (hydraulic hammer preventer? I am not a plumber).
So if I had to replace it, I would need to cut off two feet of pipe, use a dual SharkBite (if that's the correct brand) and would lose that dead end extension.
Curious if there's an easier way. None of the big chains are carrying these valves. Does anyone know what size nut is used in them?