It is fairly expensive to tie down a locomotive to a flat car, the railroads now do their best to try to launch them off despite cushion drawbars. These are too big to truck easily, but the question remains as to why they didn't follow the same route as the first two if they were going to CEECO/Progress Rail's shop?

My best guess: CEECO/Washington Corp. had to honor WP&Y's option for more rebuilds, that were to be the same specification for fleet standardization. That means they will want the same Cummins engine and electrical control system (probably custom electronics/software). I would guess that the next cores are on their way to a shop either controlled by Washington Corp. or under contrat to them. That means New Westminster shops of Southern Ry. of British Columbia or Livingeton shops of MRL. Didn't know about Western Jct, so it might be an option.