I also heard of trying this way.
Warm up transmission by driveing at least 8 miles, then on level surface put on emergency brake, chock the wheels, then put truck in all the gears then back to Drive and check oil level, if low add to full mark. Can not remember whos idea this is but it was from a reputable transmission person.
OOPPs I see someone snuck in before me while I was typeing.
If it was my truck I would never over fill the transmission. It will eventually cause transmission problems. Also if your transmission is overfilled that could be the problem (air bubbles in fluid).
Ron