I have my original under dash truck radio, had it playing on the bench some years back. It's on the shelf now and I want to do what ever is needed before installing. Also my truck is now 12v, what do I need to drop voltage to 6 v. for this old radio?

It's easier to get forgiveness than permission!
1946 1/2-Ton Chevy
1953 Chevy 3/4-ton Factory Stakebed