Complex sentence: The first batch of 75 DH-100 Mk.6 (J-1005 to J-1079) was purchased in 1949 most of them passed out in 1968/1969, the last ones in 1973.
Split into simpler sentences: The first batch of 75 DH-100 Mk.6 (J-1005 to J-1079) was purchased in 1949. Most of them passed out of service in 1968/1969, the last ones in 1973.