This particular example seems to be complete and has drawings dated to 1938. The box is marked K-2217-L, with K-1383 (the right had version) also covered in the instructions which are dated to April of 1941. Note the insulated frogs (this has parts enough to do a crossover) and also that the guard rails and points are steel stampings. A photo of the product as seen in 1938 in their “Blow-Smoke” newsletter may be seen here.
None of these are items I have any plans to use today but it is nice to have them as part of the Scale-Craft collection.