Chris,
The locomotive in question is a 1903 Porter 0-4-0T-turned-2-4-0. Frontier Town acquired it sometime in the late '50s from William Willock -- a Vaudevillian, if I recall -- who ran it around his Syosset, Long Island estate. Willock was an avid antique machinery collector and was also involved in founding the Rough & Tumble group in Pennsylvania. The little Davenport, which has most recently operated at Rome under Railstar, was also part of this collection. It was sold to Frontier Town later on, although I don't know for certain if it ever operated there. Railstar purchased both locomotives from the defunct North Hudson park where they sat significantly after the park's closure. Steam was dead even earlier there in favor of a new "steam outline" dismal.
Also, the "amusement park 2-6-2" was, if I recall, built from Davenport running gear. From what I hear, its condition, courtesy of the previous operator, leaves something to be desired.