4r70w Transmission Overdrive issue?

Nope not really. 4th is often characterized by what sounds like rpm free spinning in neutral then gear engagement which under light throttle can be a clunk. Cant adjust this as there's no line pressure since it's not maintaining clutch pack overlap being as there's no clutch pack.
 

+1 CobraRed I am really impressed how you have jumped to the top of the 4R70W tech hill, keep it up man