I am almost positive that it is a different part in how it mounts and the proper orientation than a typical Eaton.
I know I went thru great lengths trying to find one made for high lift cams at one time and ultimately gutted mine and trimmed the internal spring to delay its closing. Hopefully this is not what I am remembering but I think I was trying to get a new replacement before I did surgery on mine.
I can say it was quite easy to open and reseal with silicone. Unless your diaphragm has an actual tear in it (and you would have known as the blower would have been screaming at you even at idle or you would have zero boost or sound for that matter) I can’t see why you couldn’t open it up to check the diaphragm and spring, clean, and reseal it easily.
Your rebuilder could very well just be looking to cover his work with new parts? I’m sure they go bad like anything else but I’ve yet to witness one personally.
There should be a part number on the bracket and JonBondPerformance lists quite a few.
I’d call Jerry Barnes if you hit a dead end.
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