Help finding code for P-40 FX567, 450 Sqn

[Crimea River]

A friend at another forum is looking for the subject aircraft code letter. He says:

"I am looking for a Kittyhawk of 450 Sqn, No. Africa. 1944.
Below is some information I have found about a little op to Monte Casino by a group of P-40's in particular is the aircraft of DM Davidson, FX567. I am trying to find the code for that plane. The sqn codes were "OK*_" . I've got loads of photos, and documents regarding D.M.D. and just need that code for his aircraft. Any help would be greatly appreciated.

I have found this on the web at this site....
http://raafdb.wordpress.com/tag/450-squadron-raaf/

On This Day – 16 February 1944
At 1350 hours, 12 Kittyhawk IV fighter bombers, led by the Commanding Officer, Aus X S/Ldr K R Sands, DFC, were airborne to bomb Cassino Monastery, Italy. The formation encountered heavy 9/10 cloud in the forward area, with very poor visibility, and was forced to return to base with bombs.
Pilots from 450 Squadron were as follows:

Kittyhawk FT948 – SQNLDR Kenneth Royce Sands, DFC, RAAF
Kittyhawk FT946 – WOFF Alastair Douglas Mylne, RAAF
Kittyhawk FX549 – FLGOFF Colin Edwin Johnston, RAAF
Kittyhawk FX567 – FLGOFF Douglas MacKenzie Davidson, RAAF 402321
Kittyhawk FX547 – LT B O Pigott, SAAF
Kittyhawk FX532 – WOFF W G McConnochie, RNZAF
Kittyhawk FX556 – FLGOFF Reginald Alfred Hast, RAAF
Kittyhawk FT943 – FLGOFF Raymond Gershon Goldberg, RAAF
Kittyhawk FX550 – FLGOFF John Frederick Alexander Ellis, RAAF
Kittyhawk FX542 – FSGT Thomas Henry Anthony Mallick, RAAF
Kittyhawk FX557 – FLTLT Colin Watson Robertson, RAAF
Kittyhawk FX545 – FSGT A J C Rogers, RNZAF"

Any help on this would be appreciated. Thanks!