In July 1988, Conrail SD40s, working as head-end helpers, lead a westward Trailvan train around the famous Horsehoe Curve (west of Altoona, Pennsylvania). This landmark of the Pennsylvania Railroad was reduced from four tracks to three in the Conrail era, but remained a vital artery for freight. I’ve used a variation of this photograph in several publications including my book Railway Masterpieces.