In exchanging info with a Tekno specialist in Denmark, I was surprised to learn that the KZ.4 'Ambulance Plane' was issued from 1939-1949. But, be careful about what 'experts' claim. Only one problem with my Danish experts remarks: some quick research showed that the KZ.4 first flew in 1944! Only two aircraft were built. The white toy in the photo above is finished exactly as the preserved aircraft in a danish aviation museum and it carries the same registration OY-DIZ and 'ZONEN' on the nose.
Incidentally, the white cross in a red circle does not represent the International Committee of Red Cross. It is a national symbol for Denmark. The red flag with the white cross on the tail of many KZ.4 toys is the Danish flag. OY is the registration code for Denmark, DDL is for Danish Airlines.
The Tekno B-17, Blenheim, and the Douglas Dauntless SBD Divebomber were, according to this source, also issued in 1939. I find this also wrong due to the fact that Denmark was occupied in 1940 by Germany. Neighboring Norway, Finland and Sweden did not have any B-17s, or Dauntless SBDs of its own.
One might wonder why Tekno picked these aircraft to model in toys, but surely they are post WW II production. {Blenheims were used by Finland in 1940 in their short war against Russia.}
By 1944 several battle damaged B-17s landed in Sweden and they were allowed to keep some for conversion as transports. The glassed noses were sheeted over in aluminum and lengthened for cargo storage and the turrets and machine gunners positions were eliminated.. These were, of course, the later versions, most likely the F and G versions of the B-17, and not the early B-17 B,C,or D version that Tekno modeled. Two of these planes were later used by Danish Airlines, registered OY-DFE and OY-DFA. Several Tekno B-17 toys have the same fictitious registration as used on the KZ.4 'Ambulance Plane', OY - DDL.
There many versions of Tekno B-17s, and many nations were represented, even the civilian transports which were issued in bright colors. All the camouflage ones were hand painted identically. A white B-17 with red cross markings was also issued.
The other models also were issued in many versions. I wonder if the Dauntless with the white cross in a red roundel was a mistake. Or was it representing the Danish red roundels with a white center? It does carry the Danish flag on the tail.The normal Red Cross markings would have a red cross in a white roundel as seen on the Blenheim. In any case most all the Tekno planes had all white finishes with red or white cross variants.