D/Dart + 360 Crate Engine + 122 tooth flywheel = Trouble ?

Welcome to the world of early a bodies!. Sounds like you are using the 360 magnum crate motor? You must use an externally balanced 360 flywheel for your specific engine, magnum is different from LA. You cannot use the 122 tooth flywheel. The 360 flywheel uses the 10.5 inch clutch, which may require a different bell housing. I think the d/dart had a 10.5 inch clutch so you may be good. I highly recommend calling Brewers and telling them what you need. They hooked me up with everything I needed when I dropped a 360 in a 65 barracuda.