Towed 2a65/MSTA-B (aka M1987) has a 53 caliber barrel. Interoperable with legacy systems. The production of a howitzer 2A65 "MSTA-B " on Perm Plant would begin in 1987. SP 2s19/MSTA-S entered service with the Russian Army in 1989. Both about a decade later than Dana, which IMHO rules them out as origin of the Dana/Ondava ordnance.
2a36: Towed 152mm with 49 caliber barrel (or 54 cal, I've seen both numbers quoted). Not interoperable with 2S3 and similar legacy systems. Related to self propelled 2S5. Gun's test models passed trials in 1971-1972. It's serial production began in 1976. This would make it contemporary to Dana
The CSLA's tube artillery inventory in 1987 included 250 M-53 (100mm), 100 M-1931 and M-1937 (122mm), and 75 M-46 (130mm) guns. It also included 90 M-1937 (152mm) gun-howitzers and 250 D-30 (105mm), M-30 (122mm) towed, and M-1974 (122mm) self-propelled howitzers, plus 175 DANA (M-77) (152mm) Tatra 813 truck-mounted, self-propelled howitzers. Introduction of the heavy Soviet M-240 (240mm) self-propelled mortar began in late 1986 or early 1987; the 2S7 (203mm) self-propelled gun was known to have been in use in 1986.
So, it appear that at the time Czechoslovakia did not have any modern 152mm tube artillery in service (The M-1937 is the ML-20 152mm from 1937.) They developed Dana instead of getting the 2S3 from Russia. Since the gun performance of Dana is superior to that of 2S3, its development and adoption may also have reduced the need for acquisition of 2S5, with its separate family of 152mm ammo.
According to
Army Recognition, the ordnance of Dana is derived (probably by Skoda) from that of the Soviet 2s3/M1973 i.e. ultimately from D-20.