Procor GP20 20,000-Gallon Tank Car Ready to Run Procor Ltd. PROX Single CarDetails: Founded in 1952, products Tank Line (renamed Procor in 1962) constructed their manufacturing plant in the mid 1950s in Oakville, Ontario. Initially, engineering was supplied by the parent Union Tank Car Company. In the 1960s, Procor assembled its own engineering department and crafted a series of standard design tank cars which paved the way for a new generation of equipment, with many modern designs reflecting this new standard. The GP20