You will have to change:
- battery
- voltage regulator
- generator
- light bulbs
You will need a special-type of voltage reducer on the power side of the fuel gauge.
The 1950 truck did not have a horn relay, unless you have the accessory dual horns (6v). That relay will work OK with 12v, as will the 6v horn(s) in a 12v system (but, the horn(s) will be higher pitch and might burn-out if you hold down the horn button for a long time).
