A fascinating history of the EsPee's path to dieselization, with a complete chapter on the Diesel-Hydraulics, up till 1983. The later models are covered in relatively few pages compared to the older, obsolete ones like the E-units and other pensioned off machines, but there are publications (Joseph Strapac's "Southern Pacific Historic Diesel" series inter alia) that look at the later classes in greater depth.

The Diesel-Hydraulics chapter's opinion of the K-M locos is at variance with at least one other source: Garmany suggests that they were a success, but Signor (I think, and will have to check the relevant chapter of his book) felt they were an expensive and mechanically-fragile failure, ill-suited to US railroading because of their need for legions of skilled technicians to provide support for them.

There are plenty of photographs and detail about the programme, together with roster lists, and some background about dieselization in general.