Henry ..you are quite right about the car numbers..I was wrong about 500's.. Interesting note...You may recall that one trailer the 404 had different windows on the ends than all the other trailers....Yes There were 2 SP tracks .. and 2 Key tracks... north of Alcatraz as you confirm... the two Key tracks remained there for some time after service discontinued.. I believe another old timer who knew the Ward St yard will confirm that it contained several tracks with overhead wire ..and as you say it was switched by 1200 series steamers.. Dr Zarkoff apparently knew details of the yard suggesting Ellsworth and Calif. St trains were stored there during off peak hours.