Dudley,
Let me start out by saying that I'm not a pilot and have never flown
anything with more power than a T-34A (flown from the backseat with a
"real pilot" up front) and a P-3 from the right seat.
Would the sideslip issue have been affected by the addition of the
fairing forward of the vertical stab? IIRC the P-51B/Cs didn't need the
fairing because of the extra side area they had compared to the
D-model. The early D-models apparently did have directional stability
issues prior to addition of the fairing. Maybe the training manual came
out before it was added?
Don McIntyre
Clarksville, TN