Anything's possible, I suppose.* But because the axial hole had been bored, I don't think that it would be an 'incorrect' part -- what would be the purpose of such a part?* So it seems likely that it was defective.
The heritage of the engines is unknown.* They are 8 years younger than the hull, but no records exist as to whether they were new or used when installed.
The washers weren't correct when I disassembled it, either.* Washer 6 was below the collar fitting instead of above.
I haven't checked the*port engine yet to see if it's set up the same way.
The manufacturing year of the engines is 1979, which as I recollect wasn't exactly a banner year for English manufacturing quality - who remembers (or doesn't want to forget) British Leyland??*