Vio had confirmed that the D-51 First Try Sets track are dark gray but since they don't make a switch like this in light gray (that I know of) I think it would look better on a Layout with all light gray than using a blue one.
The other Tomica World set that I think Thara missed in the original Post may have been the very Rare Blue EMD F-unit which has a Loop of regular gray rails. Best of luck trying to find one
![[Image: 003-zpse1effe7e.jpg]](https://i.postimg.cc/8FsbWMmY/003-zpse1effe7e.jpg)
The other Tomica World set that I think Thara missed in the original Post may have been the very Rare Blue EMD F-unit which has a Loop of regular gray rails. Best of luck trying to find one
![[-]](https://www.blueplastictracks.org/images/collapse.png)