From the graph, it looks like all the La7 flyers went to the P51.
(anyone surprised?)
I have a hard time to deduct that from the graphs provided in this thread so far

But your post made me take another look at it:

When La-7 usage went down, not only P-51D gained but also Spit 16 and N1K, and the Spitfire gained even more than the P-51D. Surprisingly, it seems that the P-51 may have gained most from N1K losses after version 2.13 (Tour 106)