Here's the only catch: you have to buy two if working on a big block Mopar since the spring is for a Ford (Mustang I assume) and is too short. But each spring is only $4.92 (shipping included).
http://www.cjponyparts.com/LOWER-RADIATOR-HOSE-SPRING-STAINLESS-STEEL-BIG-BLOCK-1965-1973/p/HW770/
http://www.cjponyparts.com/LOWER-RADIATOR-HOSE-SPRING-STAINLESS-STEEL-BIG-BLOCK-1965-1973/p/HW770/