Just did an aw4 conversion on my wheeler. Gets a sound similar to a fan blade hitting something but not quite as fast. Only happens under a load, and idling in park or neutral when the jeep is on an incline. Does not do it when cruising, but give it just a hair more throttle and it does. I didn't notice any obvious cracks in the flexplate when I installed it, but I'll admit I didn't look very hard because I figured they would be fairly prominent. Any thoughts?