I spent way too much time trying to find an adapter for an oil pressure gauge. The one that came on the engine was aluminum and chewed up. I could have bought a factory plug, drilled and tapped it, but they're aluminum too.
The first adapter I bought I some how ordered the wrong size. I was able to return it. The second one I ordered was out of stock. Finally got the third one right. Got it off eBay and its steel.