MLW M420 vs. M420R

Allen Hazen wrote:(*) For those not in the know: the CE618 was a diesel hood unit with a 16-251 engine rated at 2400 hp (= roughly 1800 kw), built (by Commonwealth Engineering) in 1978 for the narrow (3'6") gauge lines of the Western Australian Government Railway: the last Alco-engined locomotive design introduced in Australia. So, sharing with the M420 the property of being a "post-Alco Alco."

2400 HP from a 16-251 was pretty standard in the early to mid '60s, but by the late '70s, that engine had proven itself capable of producing a reliable 3600 HP. Is there any particular reason why CE chose to give it such a low rating, rather than using a 12-251 (which by 1978 could reliably produce 2400 HP)?

Re: MES407's query on the horsepower.

Sorry, my mistake: the CE618 had a 12-251 engine, NOT a 16-251. (So, in 1978, CE built locomotives with the 12-251 engine at two different horsepower ratings: 2000 hp in the NSW 80 class, 2400 in these Westralian units.)

That makes sense. Thanks for the clarification.

While on the M420 topic, what wheel slip system was used? Did Bombardier/MLW have its own, or did it use the same as a U23B or B23-7?