From the packaging:
This 18xx kit augments an existing game. It supersedes previous Kits K1 and K6 and contains more tiles, 36 instead of the 15 in K1 and 12 in K6.

Contents:
Yellow Tiles: 2 each of nos. 7, 58 & 115.
Green Tiles: 3 each of nos. 10 & 11.
1 each of nos. 17,18,20,21,22,30,31,82 & 83.
Russet Tiles: 2 each of no. 174.
1 each of nos. 35,36,37,38,39,40,43,44 & 47.
Russet/Green Tiles: 2 of no. 119.
Russet/Brown Tiles: 2 of no. 200.