I'm not sure of the model, but I was looking up 51 pics, and I found a picture of a P-51A (I think, maybe a C?) with what looks to be 3 .50s on each side of the wing instead of the 2. Did this ever actually happen?
Wonder if they did that to make the enemy think it was a D model?
You gents haven't seen the Marine Corsairs with 2-3 extra painted on gunports per wing?