I've looked through my Bob Mannel bible and can't seem to find a match to my balancer. I just bought a 66 fastback that came with an extra 289. The motor has a 1965 block but the crank pulley has 4 bolts. The Balancer is part # D5ZE-6316-B2A and the crank pulley is D5ZE-6312-B1A they both look like they have been on there awhile. All that I can find is 3 bolt crank pulleys?