You need one of these
Voltage Booster #NGVB-HC for a 6 volt negative ground truck.
Important Note:
If you have the modern type 12v radios/CD/cassette, 25-30 watts watts per channel.
This type of radios/CD/cassette goes into a stand-by mode, when 12v is applied to the accessory wire.
So that the battery does not drain dead.
You have to put in a micro switch relay/memory maintenance module or a toggle switch
If you have the older type 12v radios/CD/cassette, 6-10 watts per channel.
They don't have a stand-by mode, there is no need for a micro switch relay/memory maintenance module.
You should read this
POST...
Install Tips 12 volt CD/Radio in a 6 volt vehicle The Post describes the info in more detail and has wiring diagrams.
