It might be worthwhile explaining a little of the background to my discussion with SSW9389 regarding EMD rebuilding locomotives in the early 1950s.
Let us look at what happened to the iconic Santa Fe E-1 units 2-9 and the E-2 from the 1937 City of San Francisco that ended up with Southern Pacific.
These units had the V-12 201A engine of 900 HP and auxiliaries like radiator fans driven by vee belts, and both of these were regarded as maintenance intensive by 1950, by comparison with the 567B and AC motor driven fans. But much of the electrical equipment, in particular the main generators, traction motors and even the trucks were still in excellent condition.
The preferred EMD answer was to build a set of new E-8s for Santa Fe using the trucks motors and generators from the E-1s (and the prototypes 1 and 1A). The power of the E-8s was reduced to 2000 HP due to the old generators, and these were called an E-8m.
At the time ATSF was one of EMD’s best customers and the rebuild kept both builder and operator happy. ATSF never bought another E unit, having bought passenger equipped FTs and they never looked back.
Having inherited the old E-2A SF-1 which was equivalent to the ATSF E-1s, Southern Pacific had the same problem. A new E-8 would have done the job but SP may have felt the cost was too high.
In the end they built effectively a new E-7 on the old frame with a lot of material provided by EMD.
The first question I asked was why build an E-7 instead of an E-8? Using the original frame, which was set up for the two engines facing the same way with the generator (requiring a well in the frame) at the front, the latest available design was the E-7, which had an improved layout but still used mechanically driven auxiliaries. The E-8 had the engines arranged with generators together at the centre.
But SP got its new E-7 with 567B engines and it lasted as long as the others.
To get back to FT units, Santa Fe lost an A unit, 107L and took