Audio in C20, starting from scratch

[Old Rust Bucket]

Here's the plan. Tear out the entire old audio system and replace it with a new (Pioneer) radio and new speakers. This brings up a few issues. 1) The old radio is shaft mount the new radio will not be. What parts will be needed and where can I find them. 2) Where are the speakers located on a '76 C20. These GM are new to me and I haven't yet got the truck home to look it over. I want the end result to LOOK NICE AND/OR FACTORY. I am not going to hack up an original dash in good shape to make this work.
I was hoping someone here had been down this road before and could give me instructions on how to do it easy and without hacking up the dash.


Thanks,
ORB