Complex sentence: The R10 was a New York City Subway car built by American Car and Foundry Company in 1948--1949, Unit Numbers: 1803--1852 (renumbered as 2950--2999 in 1970) and 3000--3349.
Split into simpler sentences: The R10 was a New York City Subway car built by American Car and Foundry Company in 1948-1949. Cars were numbered 1803--1852 (later renumbered 2950--2999 in 1970) and 3000--3349.