I have a solid strap on my 70 Roadrunner four speed. The motor doesn't move at all and I want to do this to all my other cars. up

56 Plaza 63 D100 step side 67 Coronet, 68 Roadrunner, 69 Super Bees, 69 Coronet 500 convertible, 70 Roadrunner Post, 79 D150 360, and a severe case of Mopar a,d,d