Sorry for hitting the wrong key and giving an incomplete post.
I purchased a reproduction pickup tailight for my 36 1.5 ton. It has two sockets, the upper containing a large lamp and the lower containing one the size of a parking or dash lamp. The green wire from the stop light switch goes into the upper and the black wire from the light switch goes to the lower. There is a divider between them and a clear lens to the license plate below the small one.
The upper light works well as a brake light, but the lower isn't much of a tail light, being fairly dim and only illuminating the lower half of the lens.
Is this the way it should be? Perhaps it is just a matter of putting a bigger lamp in the lower socket, although it wouldn't fit well under the divider?