Loud noise flywheel torque converter area

I replaced the engine with a 350 four bolt main crate motor! Now after getting it all back together they are a very loud noise coming from the flywheel torque converter area. When you give it the gas under load it will not make noise but as soon as you let off gas it starts a whining loud sound. Tried everything and all I could think it could be is maybe the crate motor had a pilot bushing in it already and I didn't see it. Is it possible it would run good and smooth until you let off gas then it gets loud.