The Short Answer is "West Side Lumber"

I am sure to leave something out so bear with me:
All three shays come from The West Side Lumber Company in California
The Number 8 is the heaviest of the three at about 75 tons and was delivered new to the WSL Co. in 1922. The 8 along with the 9 and 10 were the three heaviest on the West Side Lumber and were considered "Towns" engines. They would bring empties to the halfway point and exchange them for loaded Skels and bring them to town.
The 12 and 14 are smaller Shays at 60 and 65 Tons respectively. They were considered "Woods" Engines. They would take the loads from the wood to the meet with the "Towns" engines for the swap. The Westside liked having the smaller shays in the woods on the newer track and the heavier Shays on the "Main" into town. The 12 was acquired from the Swayne Lumber company in May 1940 (were it was number 6 and before that it was Butte & Plumas Ry. number 6) and the 14 (along with sister WSL CO.15) was acquired in 1939 from Hobart Estates Co. were it was Number 10. Prior to that it was Sierra Nevada Wood and Lumber, were it was Number 10 also. (The WSL 15 was the Hobart number 9)
OK everyone; fill in the blanks...
Kevin