Built in 1895 (A to H) or 1896 (I, J) as a mail car.
Electrified in 1898. Acquired by Metropolitan Street Ry. in August, 1900.
Converted to service (supply) car by Metropolitan Street Ry. after the mail contract ended in October, 1900.
Returned to Third Avenue Railroad in 1908 and eventually renumbered into 2–10 series of the Union Railway.
Former number unknown. Could have been 10 prior to 1911.