It was originally Lisunov Li-2 (Soviet built DC-3), serial number 23442209, Czechoslovak Immatriculation OK-GAD. Plane was rebuilt in Aero Vodochody from September 1967. Replica (in nonflyable conditions) was carried by truck Tatra 141 from Aero Vodochody Works to Klecany Airfield (one of base of KG (J) 6 in 1945 and airfield was abandoned by Czechoslovak Army before filmnig).
Plane came to the Československé aerolinie (ČSA, Czechoslovak Airlines) in 1952, in 1956 to Czechoslovak Air Force, rebuilt as Lisunov Li-2F, coded 2209. Out of service August 1966. Another fate after filming unknown me. Filming took place between April 1 1968 and August 19 1968.
http://www.planes.cz/lite/data/fotografie/2209_Li.jpg
Hope this helps
Michal