The ground crew painted numbers on the guns and ammo boxes so that they stayed with a particular aircraft. This was done so that when the guns were removed to the armoury for servicing they could be returned to the actual position they were removed from and therefore gun harmonization would not have to be repeated. I have seen several examples of this.
Ammo boxes were often also marked so that a particular mix of ordnance would go on a particular aircraft and operation. ie HE, AP, tracer etc.

If the Air Attache is going to the aircraft I hope that he is briefed on the elementary aspects of identifying the aircraft. Anybody with P-40 experience could easily open the cockpit without damage, yes after all these years, and get the number from the longeron. Jettison mechanism was changed over the years but the hood winding mechanism is easily dealt with. Distortion to fuselage appears further aft.

The tail strut should be the next port of call, this will give additional information as to contract and hopefully a/c serial. Whilst I have seen US serials on struts I do not recall a serial on the a/c recovered from Russia. Identity was based on the longeron serial.
Other areas to look at, guns and ammo boxes often have painted serials, main gear has been mentioned but is not accessible at this time.
It is possible but not likely that individual data plate could give a lead.

Anybody seen the remains of the parachute pack? Whilst serving at Abingdon with “Crash & Smash” I was asked to recover the remains of a Hurricane and it’s pilot that had crashed near Spadeadam and to identify aircraft and pilot. Both were easy as the serial was found on a piece of wooden structure and the parachute pack had the owners name on it. Parachutes are a personal piece of kit.

Each time you look at the video you see more. Note flak holes visible inside the fuselage stbd. side, port tailplane one hole, top rear fuselage damage and of course the exit holes by the hatch port side.

Further to previous post on canopy winding handle, the lock peg can engage one of two holes as it rotates. Further observation is that the ignition switch is “OFF”.

Procedure for engine failure during flight;
Maintain 100 mph
Land with gear retracted
Fuel off
Ignition off
Lower flaps
Battery off
Open cockpit
Land with as high an angle of attack as possible

Have had a quick look through the P-40 drawings and so far this is the only one I have found for “the door”. Drawing number 87-21-526 shows different safety method.

As regards markings 75-88-465-289 shows lots of decals including North Africa Stars and Stripes, Brit and US markings but not “the door” markings.

Will continue the search. Could be the door change was issued as a Technical Order or to us Brits. a modification.

Some recoveries where paint has not faded.

Another unusual aspect is that modellers usually show bullet entry holes, these are exit holes for bullet or shrapnel just aft of the oil tank. Could be the oil tank was hit causing loss of oil and engine to sieze. Notice also above the roundel where shrapnel has hit on the inside but not pierced the skin, just left of the small panel.

Also note where hatch has been forced open by distortion of the fuselage the security dzus fastener has torn through the hatch skin flap below the hand opener.

Have you also noticed discolouration of side perspex? Is that what would happen in that environment?

There is just to much detail in the hatch shot to dismiss the photo out of hand. If it is from photo shop or manipulated in some way it is the work of a genius who really does know this aircraft.