Built for the National de Mexico railway, Alco C424 #B906, along six sister units, was delivered instead to the Wabash, which was short on power. A road crew and a couple of hostlers, with whom I spoke not too long after delivery, were frustrated that the locomotive controls were in Spanish. Hence, the seven centuries were used as booster units. B906 is seen here after the N&W + NKP + Wabash merger. They became N&W 3900-3906.