Is it the sticker on the air cleaner????

I believe they labeled them HP when they have 2+ versions of the same cubic inch engine.

68-71 383
66-74ish 440's

340 4bbl and 426 street Hemi only came one way in each model year so it didn't say HP on it, but they all were.
Right! Even the 73 340. It was an HP engine, just HP within the gubmint regulations.