Complex sentence: Car 3200 was not only the final car of the 2600 series order, but was the final railcar to be constructed by Budd/Transit America, and once the order was complete, Budd had shut down its railcar business.
Split into simpler sentences: Car 3200 was not only the final car of the 2600 series order, but was the final railcar to be constructed by Budd/Transit America. Once the order was complete, Budd shut down its railcar business.