Germany delivered a total of 15 fighters Messerschmitt Bf 109G-6 to Slovakia in 1944. In contrast with Bf 109Es delivered earlier in the war, which were all service weary machines employed previously by the Luftwaffe in BoB and N. Africa, these 15 Gustavs were all newly build machines. They were build by Messerschmitt factory at Regensburg and flown to Piešťany by German pilots on 26th January 1944. (Fourteen Gustavs reached their destination, while one force landed on Reich's territory due to the engine trouble and was later delivered to Slovakia by rail.) As such, Slovakian G-6s wore standard German fighter camouflage of the time consisting of RLM74/75/76 color scheme. It is believed that RLM02 color was also used in fuselage mottling. Spinner was painted with RLM70-Schwarzgrün with 1/3 white segment, while propeller blades were in RLM70.
Aircraft were delivered to Slovakia wearing German national insignia, but curiously without fuselage code letters. Upon their arrival swastikas and fuselage crosses were painted over probably with RLM74 or RLM 75 and Gustavs received Slovak national insignia - Slovak crosses applied on the tail and wings. Crosses painted on the wings were placed in such manner to cover German crosses (Slovakian crosses on the wings were of larger dimensions then the German ones - see detail on picture 1 in the attachment). After some time original German crosses on the upper wings started to show through on some aircraft.
Gustavs were allocated to Letka 13 (13th Readiness Squadron of Slovak Air Arms) and Cvična letka (Training Squadron). Machines used by Letka 13 were given tactical markings - yellow fuselage band (not to be confused with Eastern front theatre band) and white numbers (1-9). Machines used by Cvična letka received no additional markings.
During Slovak National Uprising only two Gustavs (Wr.Nr. 161725 and Wr.Nr.161742) were used by the insurgents, initially both in their original SVZ markings. Some time after "161725" had been lost, the surviving Gustav received improvised insurgent's roundel (placement of which is shown on the picture 2 in the attachment).
Source of info and color profiles: HT model Special No. 909 "Messerschmitt Bf 109G-6", Artist: Jozef Anďal