Ha, a typical James picture
Nice and interesting armament.
Descriptions of it differ. IIRC wikipedia refers to the guns being of "DRP" type and many sources claim that it'd be "75mm APK" ones (which in fact were 76.2mm APK-4, installed on early versions of this kite), actually what's shown here are the tail ends of the 37mm version of APK-11, aka "APK-37", installed on the last batch of 50 aircraft produced of this type.
That much for the hints, now it's up to you to guess which version of the F-35 it is
Cheers!
Mike