[LuckyScott]

I use Custom auto sounds. They make great stuff that fits the stock opening. You can go conservative or wild. In my 70 truck I went with just the radio and a dual speaker that fits in the stock speaker location under the dash.
In my 72 suburban I did the kick panel speakers and door speakers. (Previous owner had already cut the holes in the doors so might as well fill them up with speakers)
and then I installed a subwoofer under the back seat. Sounds awesome.