Sorry, Allan, it is on a Dodge. It says to check it HOT, idling in Neutral. That way the fluid gets pumped back into all the places it drains out of while it's sitting. If you just fill it to full, fire it up, and take off, you will be running two quarts or so low.
When you have the pan off, take a look along the driver's side of the valve body. I don't know if they changed it with the electronic governor, but on the hydraulic governed transmissions, all you need is a 3/16 Allen wrench to turn up the line pressure. If you find a screw where the wrench is in this picture,
modify a 3/16 Allen wrench like this:
and give it two swings CCW, wrench toward the back of the truck. That turns up the line pressure.
Like I said, I don't know if the procedure is the same for the RE transmission you'd be getting, as the RH transmissions in the earlier trucks. Here is the whole thread on doing the trans adjustments on an RH transmission.