First gen Barracuda stereo options

What and where does everyone do for rear speakers in a 64-66 Barracuda? Anything clever?

I've seen several, including one that I just got, that had speakers installed in the "fold down" trunk closure panel. It's an easy way out as far as installation goes, but why would you want speakers on a portion of your car that was intended to be folded up and down to allow the loading of baggage or what ever. There are spaces in the rear interior sheet metal structure, right below the big rear window, just forward of fold down panel that could be used to install some speakers. I'm like chryslerfat...I like the roar of the engine.