Trans help for a friend needed

when going from park to rev and it bangs hard try this hint. first pull the lever all the way to LOW then to rev. mostly this is 1. idle set to high. 2. converter stall to low for the cam. 3. the rev / low band is set to loose. or damaged. number 3. is the most common thing. if need be call these cats http://www.areds.com/.................have known them since the late 60s. they can answer ANY Q.