This one turns out to be pretty unusual. Like a scaled up logging Mallet.
Class MM-3, 2-6-6-2
2 units acquired: 3930, 3931
"Acquired from the Verde Tunnel & Smelter RR which ran from Jerome to Clarkdale in Arizona in 1943. They were the last compound locos in service on the SP and were scrapped in 1954 and 1951 respectively."
[
espee.railfan.net]
Image hosted from here: [
www.ebay.com]