I got tired of asking the guys at the parts stores to look up the part number only to have them say that they couldn't find it. Most of the places I called won't be able to find it on their computer if you ask for the part number - you need to ask for the stock number instead. Anyway, here is all the MR2-specific information I could extract from the catalog. I'd recommend you get yourself one if you're interested in this stuff and don't have one already - it contains some useful information. The first digit in the NGK part number indicates the heat rating.
Lower numbers are hotter, higher numbers are colder.
If anybody has some specific applications they'd like me to look up, please feel free to email me privately.