Before that, they put PACARD (sic) wheels on an older model - the ambulance and mail truck. Same casting, just different colors and decals came out in 1947 and lasted until 1955. Thus, these are very old and some of the first diecast metal cars that Tekno made in Denmark! White and red ambulances were made for the Danish market, with ZR decals for Zonen Redningskorp (Zonen rescue society). The post car version came in yellow for Danish Post and green for US Mail (US, I assume).
