Hi,
I suppose people are using retailers such as below!
Possible suppliers:
http://www.gsparkplug.com/shop/Interesting article:
http://matchlessclueless.com/mechanical/ignition/spark-plugs/A old motor-Factor retailer in Ramsgate, Newmans had all sorts of old stuff in storage from yesteryear, the wife of the guy who ran it, now deceased, (who still opens the shop at the Weekends), told me a couple of years ago, she had been approached by someone who sought to but her entire stock of old parts, for cash, I imagine this stuff found its way onto the Web or down @Beaulieu. I still amazed what original stuff still appears there, often boxed & definitely OEM stuff.
Although this term can be now confusing due to modern nomenclature:
1) Originally, an OEM (original equipment manufacturer)REG was a company that supplied equipment to other companies to resell or incorporate into another product using the reseller's brand name. For example, a maker of refrigerators like Frigidaire might sell its refrigerators to a retailer like Sears to resell under a brand name owned by Sears. A number of companies, both equipment suppliers and equipment resellers, still use this meaning.
2) More recently, OEM is used to refer to the company that acquires a product or component and reuses or incorporates it into a new product with its own brand name.
http://searchitchannel.techtarget.com/definition/OEMBuyer Beware!
Cheers
JBW