Verm,
I have a copy of the manual too. The weight table in the back list three separate loadings. 17,400lbs, 19,400lbs and 21,400lbs for the P-38L. I can't seem to figure out which one represents 100% fuel and ammo.
There have been so many whines about the 38's performance I figured I would try to get to the bottom of the stall speed but if I don't know what 100% loading condition is, it is hard to say if the AH model is accurate or not.