Kicking cars at Smith Avenue, we are close to Mile Post 4.2 on the Union Pacific Los Nietos Subdivsion. In Southern Pacific days, this was Mile Post 500.7 on the Puente Branch. SP never saw a Genset, of course, but the Gensets are slowly taking over much of the SoCal switching and local assignments. 3GS21B #Y2722 was delivered by NRE on May 30, 2007. GP15-1 #Y641 was delivered to the Missouri Pacific as their #1641 in October of 1979, making it 28 years older than its mate.