Complex sentence: Therefore, a less ambitious plan to rebuild the Class 690 by replacing the boiler and firebox with those of the FS Class 746 was approved; from 1928 to 1934 all thirty-three locomotives were rebuilt into the new Class 691.
Split into simpler sentences: Therefore, a less ambitious plan to rebuild the Class 690 by replacing the boiler and firebox with those of the FS Class 746 was approved. From 1928 to 1934 all thirty-three locomotives were rebuilt into the new Class 691.