They are out there for the n52.. or used to be. It’s not worth the hassle in my opinion. I’ve replaced them on n52 and n55 only to buy a little time- more so on the n55 because it has other integrated valves that harden and rot.

Better to just get a URO or genuine assembly which comes with gaskets, hardware, etc. I’ll see if I can find the p/n for the n52 valve tomorrow.