Serial Number 1506:
This D-44 was Polish made in 1956.
Modernized in the 1970's with the addition of an electrical system and lights, it was referred to as a D-44M for modernized.
Still in use in a few countries and has been observed in Ukraine.
Very nice original condition obtained directly from the Polish government in 2015. Ukraine subsequently bought the remaining cannons they have been observed in use.