My landy is a 110 commercial, and I didn't have (or just couldn't find) any wiring for the radio so I wired mine in using small block connectors.
As above, you only normally need three for the radio
Ignition switched live so you can't leave your radio on,
Permanent live for the channel presets,
Earth.
Speakers are easy, depending on how many you have, just get some speaker cable, run
in pairs using block connectors.
Only disadvantage I can see is you need to unscrew the connectors if you want to take the radio out, but it's hardly an every day issue.
I picked up the feeds from the rear window wash wipe and ciggie lighter.
Put mine in a mud console,
Hope this helps
Rick