I ordered a replacement oil pressure sending unit from rockauto.com. I purchased the Beck Arnley #2011397.

It looks very different. It's much different in size and it has a much longer thread. I'm hesitant to attempt to install this for fear that I'll damage the threads on the engine. Has anyone used this unit from Rockauto?

 

the threads are NPT, or rather BPT so the length doesn't matter. just tighten it down until it seals is all that is necessary. the dimensions are different because it's a different sender unit construction than the mazda OEM unit but it should still work fine.