Bart-
I looked up what I had on the Byron Railroad; turns out that the two locomotives were found at the Davenport Locomotive Works (I presume they were Davenports then). They were boiler-less; and he got the boilers off of stationary and traction engines (which from what I've seen, can cause major problems...I don't know about these).
The two locomotives ran from 1950 until an unknown point. I guess they went straight to the Monroe, WA private owner. I did talk a long time ago with the family member handling that sale; the other locomotive (2967) had left the property with some of the rolling stock previous to the sale of 2968. The locomotives and some of the cars all had names significant to the builder/owner's family members. The numbers were taken from full-size engines; I forget from which railroad. Some of the rolling stock was taken from a Burlington Northern road train or something!
-Ed Kelley