Speakers for the Custom Autosound systems

[Coley]

I recently bought a (used) Custom Autosound Am/Fm/Cassette system for my '72 but I'm currently short a speaker (or 2 or 4 LOL).
Anyone know the best set up for these stereos in terms of speakers?
I thought there was in in-dash one for these but I think I would prefer that working in tandem with some external speakers mounted somewhere?
Anyone have any leads on anything like this or suggestions?
I'm not a heavy duty audiophile so I'm not immediately expecting great things....but it would be nice to get a little more variety from the radio/stereo/unit than what my current original radio puts out.
My truck is an a/c truck so ideally I only one to do the radio/stereo/speaker changeout only once
Many Thanks
Coley