The marker lights were easier to make than you might think. After reviewing some measurements shared by others, I concluded that some .1x.1 square plastic stock would be about right for the lamp. They appeared to be about 24" high so that meant that 1/4" would be close enough for me (Remember, these are stand-in models). The lenses are simply very thin disks of .08 round plastic stock. I cut several of them before I got the hang of cutting them thin enough to look right. Finally, the top is another .08 disk. I also rounded off the edge of the top before I glued the top disk in place.
Once again, a picture is worth a thousand words. I did drill one hole partially into the side of my lamps that had no lenses for mounting purposes. Once everything dried, I cut them apart and set them aside for later. Don't forget to make two of them. : )
My philosophy on modeling the underside of cars is that I'm not planning on wrecking them so I'm not planning on having people actually "see" the underside! So the detail here is very Spartan. I used both car floor castings as the ones sent with the cabooses were actually for a slightly different car and had one end rounded a little. Not wanting to fool around with filing that to shape and drilling holes, I simply used them both, simply cutting them in half and using both good ends. The modified versions of the 1000 cars only had two truss rods so I cut off the inside queenposts from the castings provided and put them in place. I also used the brake cylinder that was provided. You may want to use a different kind of brake gear based on the specific model and/or era that you are modeling. Finally, I glued the two parts together with a little bracing and set them aside to dry.
The Tichy turnbuckles were an afterthought but I think they add a nice touch to the model. I had tried to use wire for the truss rods but that was too unwieldy to work with. Besides the traditional string that comes with the MDC kits was impossible to thread through the small holes of the turnbuckles. So I took Ray Breyer's advice and used monofilament fishing line. I made sure that the mounting holes on the car floor were clear and put the line in place.
Remember, I still have some caboose kits available that are the basis for the kitbash. Contact me at firstname.lastname@example.org