The Athearn Ready To Roll GP35 is based on Rail Power Products tooling and represents a phase 1a version of the locomotive that was produced from October 1963 to February 1964. This was arguably the most widely used variant of the GP35. Some of the spotting features of this phase captured on the model include triple louver sets on the battery box covers, open top 36" radiator center fans, flat bottom cab number board housing, flat inertial air filter hatch, thick side sill and low profile fuel tank. This attention to detail makes the Athearn Ready To Roll GP35 the first choice with model railroad operators.