6 quarts is 6 quarts regardless of what the stick says. The stick could be short, the tube could be long and the last thing you want to do is overfill and cause foaming in the engine.
I would drop in 6 quarts, run the engine, check the oil level a couple of hours later and use that mark on the dipstick as the "normal" benchmark. Also, I believe the oil does not have to be on the full mark, just within the "shaded" area to be considered "full"
2001 F-150XLT SuperCab, Silver, 4X4, AOD, 5.4L, 3.55LS, 17in Rubber, Sport Package, Bedliner, Sliding Rear Window and A partridge in a pear tree...