Hot Rods T350 over full?

With the engine off, the level of my T350 is above the filler neck seal, as it leaves a puddle once shut down. The level on the dipstick is right (checked hot in "D") according to the marks. I can replace the "O" ring on the filler tube, but the fluid level should'nt be above this when off, should it? Or maybe I have the wrong dipstick? It drives and shifts OK.

 

With the engine running, the transmission pump sucks fluid from the pan into the torque converter and cooler and some areas of the trans. This combined with the fluids' slight expansion from heat, brings the fluid to the 'full' or cross hatch area on the dipstick. When the engine is shut-down the fluid drains back into the lower portion of the trans, to above the typical operating level. This is when the dipstick will appear to read overfull.
You should check the filler tube o-ring ( or in some cases a rubber boot). A very light smear of RTV on the o-ring before installing is acceptable. Also inspect the kick-down cable and accumulator housing either side of the filler tube; they can also be sources of leaks.