'Dave,

The plate that the points are attached to bears the number '1112403' with serial '1K24' as shown here:

http://i1195.photobucket.com/albums/aa397/fourbrads/DSC04224_zps37f2c488.jpg

Does that help? I think this dizzy is original to the truck, but don't really know. A new one is on my quest list for the junkyard tour in February.

Jim

1957 Chevrolet 3100 Stepside
235, 3-speed w/OD
In the Stovebolt Gallery