@Bill Swatos- Bill in answer to your question about premium versions of the SP style caboose ... yes some premium versions were made. They came in several levels
a. First was the addition of some much more colorful livery plus illumination and a smokestack - This is illustrated by the 6657 from 1957-58 which came in a really neat yellow / black / grey color scheme with an add on smokestack plus lighting. It did not have however automatic couplers on both ends, just one.
b. The next level was the 6357 which was not too different from the 6257 except it had a clear plastic insert that went inside all of the windows and it came with lighting and a smokestack. This caboose was produced for an extraordinary length of time, 1948-1961 and came in a wide variety of configurations. Again only one automatic coupler and it was made in browinsh red, bright red, maroon, and Tuscan
c. Then there was the 6457, probably the closest to a "premium" model that is reasonably available. It was lighted, had ladders to the roof from the platforms, smokestack, battery box underneath, two brake wheels and two automatic couplers. Available 1949-1952 so it is almost a sister in time to the 6257 from my post but with lots more details. It came in gloss brown, flat brown, brownish maroon, and maroon.
d. Finally came the 6557, which came with a smokestack with a smoke deflector and a smoke unit inside. It was made in Tuscan, and dark Tuscan. This is very scarce and difficult to find. It was also illuminated, had one brake wheel at the rear, and one magnetic coupler. It was part of set 2521W that came with the 746 short stripe tender from 1958.
Best Wishes
Don