They are a common badge for all 396 67 Camaros, 65-67 396 (ss and non-ss) Impalas and Caprices, and 65-67 ss396 chevelles.
If your truck is a custom - go for it. If not, I'd stick with the stock '69 396 emblems, they just "look right" in my opinion. But, then again, that's just MY opinion, so that means about zero. Yours is what matters - if you like them, then go for it! I think under the side marker light might look best - 2nd choice would be under the fender side nameplate.
And they are gorgeous emblems - had them on my 65.
