Another experimental member of Pennsylvania Railroad's K-4s class, No. 5399, poses in Chicago on December 14, 1947. She has the repositioned headlight and turbogenerator applied to many of the K-4s class in later years, though not the solid steel pilot. Most notably, however, No. 5399 displays her Franklin type A oscillating cam poppet valves and front-end throttle, a conversion carried out by Lima Locomotive Works in 1939. According to Carl Weber, who supplied the image, this modification resulted in a 44% increase in drawbar horsepower at 80 miles per hour, an advantage that influenced the PRR to apply this type of valve gear to the T-1 duplex drive in place of the more conventional Walschaerts motion. No. 5399's side skirting also anticipates the T-1 styling. No. 5371 rolled off the Altoona erecting floor in 1924.