I have to find out more about it, as you might be right (I think you are

) anyway that little that I knew about p82 was that when they started the project XP-82 they removed left and right console of the wing respectfully from 2 A/C P51's... also they took off both stabs...
Next thing I know that there was order for 500 P-82B (may be the B version was reworked from original concept? will look for it tomorrow) but were build at first only 20, among wich 3 were used as night fighters C and D models... Next order was for 250 fighters in 1946 - and bla-bla-bla

So it might be that original concept was actual p51, without any structural changes and longer fuselage, itself that was used as prototype...
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Best regards
Dmitry aka vfGhosty