Complex sentence: Towed versions of these guns used the same carriage: 52-L-504A (Russian designation 52-Л-504А), so installation of an A- 19 instead of an ML-20 gun was not a difficult task.
Split into simpler sentences: Towed versions of these guns used the same carriage: 52-L-504A (Russian designation 52-Л-504А). As a result installation of an A- 19 instead of an ML-20 gun was not a difficult task.