This is your best bet concerning your desire in finding the decal set:
https://vodnik.net/pages/Echelon/T35003.htm
Apparently they are out of production. You could try scanning the image and make your own decals.
Or try looking here:
https://redfroghobbies.com/products.php?cat=26&scat=133&prodline=Echelon_Fine_Details