The shop manual I have shows wiring for "optional" turn signals. It covers 55-59. The GM Heritage site has no mention of Turn Signals and the 1959 Supplement to the 55-59 Shop manual does not mention T/S. So assume that actual factory was not offered until 1960.
Assume that T/S was still an option or accessory in 59, as evidenced by your 59 wiring. In 1958 and 1959 trucks were probably "set up" for turn signals by using a modifiable connector. You are probably able to push in a contact, not sure. At any rate, it is all wired as I described. You will need 55-149 or 47-905 to modify your park housing. Not sure which. If you need to abandon that one-contact rubber connector and just wire the park/turn direct, that is no big deal and probably easier for you.
The next issue is to determine that you have a turn signal switch inside your column and you have it's harness coming out the bottom area.
So the plan is:
1. Modify the socket in the park light housing to accept a dual bulb using the available parts linked AND other 58-59 members advice on this.
2. Confirm your column has an operating turn signal switch. Probably does.
3. Find the harness from it. If it's a GM column, the colors should help in the wiring hook up. Piece of cake.
What is going on with the rest of the wiring? Stop and turn in the rear?
Just saw your new post as I was typing and thinking. Problem solved? I guess, if you add another contact, and wire, to the mate of that amber light's connector. As you can see, the contacts are not parallel, they are perpendicular to create a "keyed" plug in. Don't forget, you have to splice one of those wires to travel to other side of truck. My wiring explanation is on page 1.
FYI: You don't need amber, you can use most of what you have to save money. Buy a clear or amber lens if you need lenses. Take the unit off and go to the bench to add a dual socket.................or all new is fine with me. It's your money. Could be way easier for you.
