My '79 had a spring when I bought it. It went missing back in the car's semi-pro street days in the early '90's and is nowhere to be found.............
The '79 parts catalog doesn't show a spring so it could have been added by the original owner for some reason or,,,,,,,,,my car was built in late June '79 and has certain parts that were technically 1980 model year parts so who knows. Odd built car.