You guys are making things way too complicated. For '84-87 CRXs, if you have a sunroof, fuel injected engine, and a rear windshield wiper, it's an Si, end of story.
If it's not an Si, check the rear drum brakes. If they're aluminum, it's an Hf, if they're steel, it's a std/DX.
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-Harry
AIM: NDcissive
CRX and Pre '92 Civic, Engine Tech and Tuning, & Track and Autocross Forum Mod