easy slant 6 question - please help

Most slant sixes did not come with a bolt in the harmonic balancer, however it is threaded to accept a bolt. Go to your hardware store and buy a 3/4" - 16 x 2 1/4" bolt and appropriate washer. Anything longer than 2 1/4" will hit the back of your stock fan blade. It sure makes turning the dampner much easier. It won't hurt to leave the bolt in.