EMD F3A units 810B and 804A bracket an unidentified B unit in this photo my brother took in February 1958. At left, Alco S2 No. 1001 idles near the partially open door of the diesel house. Unit 810B was retired in 1977 and rebuilt by Morrison-Knudsen for service with the Massachusetts Bay Transportation Authority as FP10 No. 1111. No. 804A was traded in to EMD in 1969 on an order for GP38s.