@John's Trains - John, sorry for taking so long to respond, but I lost track of where your input was placed. Congratulations on selecting that handsome Marx 6000 F-3 AA diesel. This locomotive was introduced in 1950. Now you need some cars. Although they can be used to pull nearly anything, Marx did market a few sets with the 6000 as power. These, for the most part, came with what collectors call 7" cars. These are tinplate, lithographed cars, all 4 wheel and typically with tab/slot couplers or post 1953 with plastic knuckle couplers. Fear not however if you find a knuckle coupler for the great majority the "tab" of the tab/slot coupler will slide into the knuckle and give you a link. The sets came with the following cars:
1. The grey / red PRR boxcar. Any number in the series from 37950 to 37959
2. The 80982 Wabash gondola - yellow with black "WABASH" on the sides
3.1235 SP caboose, orange.
There were 4 sets but all came with the same cars (the difference between the sets was mostly in the amount of track that came with them and the transformer). Here is a picture of the cars, sorry I don't have the caboose.
Best Wishes, good luck, great train, all the best with it. OBTW...RUN IT Marx trains LOVE TO RUN.
Don
