P-38 Lightning, J or L model.  You can tell because  the engine intercooler is mounted und

P-38 Lightning, J or L model.  You can tell because  the engine intercooler is mounted underneath the prop, as opposed to being in the leading edge of the wing as in earlier models.  Those had been designed for the less powerful engines of the YP-38 prototype and never really worked well in service.

…Wait, what else was I supposed to be looking at?  I don’t get it.