Battery, alternator or something else

[forestb]

I was driving today in my 62 c10 with a small block 350 and a 700r4 and it’s about 92 degrees outside. I start hearing a clicking sound from my ac which is running at full blast. I also noticed that my radio was cutting out when the ac was ticking. I thought o crud is something wrong with my ac motor. I turned off the ac and went to roll down my power windows and noticed that the radio goes out when the windows are running. I stopped at an auto parts store to buy a sun shade for another car and when I tried to start the truck it just made a ticking noise. I didn’t look at my volt gauge at that point. I removed my battery and had it charged for 30 minutes and then checked and it was bad. 6 year old battery. So I bought a new one. The truck stars right up like normal. I start heading home with ac running and radio playing and when I am around a mile down the road I look at my volt gage and it’s reading around 11 volts which seems low. So I turn off the ac and it stays in the same spot. I get home and let it idle and it doesn’t move it just stays at 11. I am used to it being around 11 or 12 volts. Did I get a bad battery? Is my alternator bad and I killed the first battery? I have plenty of ground strap going from engine to frame to cad. Maybe my engine to battery ground is loose. My wire to the alternator is tight and my belts are tight. I have hydro boost brakes and when I first started the truck I could hear a belt squeal when I pushed on the brakes but that went away quickly. The belts are tight.