The guy I got my truck from hacked the hole in the dash for his DIN cassette player. It looks like he just took tinsnips to it and bent back the metal to make the space, then hacksawed a hole in the plastic gauge trim. At least he covered it up with a nice stereo conversion plate.
If that wasn't the case, I would have installed a $30 Autozone shaft radio, it has an input on the front. My truck appears to be an original radio delete, there was no stereo wiring or factory speakers anywhere. I got speaker brackets from a junked Sub and used some F@%&d speakers I had lying around.