transmission replacement

hi a friend of mine had a transmission put in it shifts gears right. all of the torque converter bolts are tight the only problem is a sound it makes it sounds like a rapid tapping sound ,only on idle after accelleration it goes away and when it idles bk down it kinda comes back and goes away faintly i think its the dustplate the fly wheel could be bent tapping against it off and on tell me what ya think