1991 200TDI oil pressure relief ball

I'm currently rebuilding a 200tdi oil pump, and the manuals show a small ball in the pressure relief system. I've been unable to find mine, and I can't find a part number for it anywhere. Can anyone tell where i can buy one, or if i even need one?

Ball acts as valve seat and is an essential part.
I bet yours is in there otherwise engine would have blown.

How would that cause the engine to blow? if anything surely the oil pressure would just be slightly lower?

I think he ,means the oil pressure will be dramatically lower and that is what will kill the engine.

He means, no ball, no oil pressure!!

Think of it as a valve, when oil filter blocked or oil to thick the oil forces against the ball and the spring the valve then opens to allow oil to flow around engine, if there was no ball the oil would take the easy route back to the sump and you would have zero oil pressure and a blown engine.