And if you think I even remotely had an idea of the answer... you're WRONG! I don't know much of anything about aviation other than using commercial airlines to travel....
What was the difference between the North American P-51D and P-51K Mustangs?
(and yes, I had to check to see what it even looked like!)
The height of the tail fin, the "K" model was taller. It also benefited from a weight reduction study that NAA did on the "D" making it a little bit lighter. Also the "K" was only used in the PTO flying out of Iwo Jima.
It still is a good looking Airplane today, looking fast on the ground or in the air!