Perhaps the 1951 Accessories Installation Manual can help with routing the wires for your right hand tail light. Can't help you with wire colors, connectors, and bulb configuration inside the housing.
> CLICK - 1951 986299 Right-Hand Tail Lamp

Not sure what was available in '48. I saw some references to the right hand lamp in the '29-'54 MPC in groups 2.662 and 2.665, but nothing specific.
> MPC Group 2.662


- Lonnie
My '54 3104
Photos that I have shared on Stovebolt via PhotoBucket are no longer available. Please contact me if you want a photo from an old post.
lonniecook [at] aol [dot] com. I sold my '54 3104 12/12/2017, but I still visit Stovebolt.

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