不像其他同型車輛都已經被改造成為柴油機車，此輛機車依然使用原Leroi Model RX1V, 250-HP, V8汽油引擎、排氣量為2008立方英吋。傳動方式為離合器及四段變速。
這輛機車經由博物館志工粉刷及整修，在2005年命名為George E. Holt來紀念機車長期照護者。在維修後這幾年下來，依然維持可運作情況，並作為博物館內的運送機使用。不幸地在2011年4月因為空氣壓縮機故障連帶使得引擎前齒輪造及散熱器受損，目前持續修復讓它能早日回到服務，博物館已經買了兩個原先使用在棉花軋棉機的同型式引擎以做為維修之用。
Built in a group of 24 locomotives for the U.S. War Department, serial numbers 4441 to 4464, this serial number 4463 was the last member of the group delivered on March 26, 1943. It was assigned number US 7595, and stationed at the Army Air Corp’s Victorville Advanced Flying School, in Victorville CA. In November 1966, it was sold to private company M. Lummis & Co of Richmond CA. It was later owned by Pacific Railroad Contractors of Torrance CA, and finally Railroad Builders of Mira Loma CA, who donated the locomotive to the museum in 1988.
Unlike many of this type that have been refitted with a diesel engine, this Plymouth ML-8 locomotive still has the original Leroi Model RX1V, 250-HP, V8 gasoline engine with a displacement of 2008 cubic inches. Power is transmitted to the wheels via a clutch and 4-speed mechanical transmission, with chain drive to the axles.
The locomotive was cosmetically and functionally restored by museum volunteers. In 2005, in honor of the locomotive’s long-term caretaker, it was named the "George E. Holt".
For many years after its restoration, the locomotive was maintained in operating condition, and was used frequently for switching cars on the museum grounds. Unfortunately, in April 2011, the integral air compressor failed, which caused extensive collateral damage to the engine’s front gear casing and radiator. Work is underway to make the necessary repairs and return the locomotive to service. The museum has purchased two stationary Leroi engines that were originally used to power cotton gins, which will serve as a parts source for the Plymouth’s engine.
車輛外觀，2017/02/12拍攝於Arizona Railway Museum
解說牌，2017/02/12拍攝於Arizona Railway Museum