As far as i know M636C dumpers 1,2 and 3 can accept the SD70's and i believe it was only dumpers 1 and 2 that needed modification which was carried out as part of the upgrades they have both received in the last year or so,and as you have mentioned dumper 4 was a new dumper so could take the SD70's from when it opened.Thanks to you for chasing up the info on these new SD70's and the tip on the Trains forum,i have just read that CSX's fleet of AC6000's are to get an engine change to an Evolution series engine rated 6,000hp creating an ES60AC,this may or may not be relevant to BHP's AC6000's,as in upgrading them to Tier 2 Locos.Slightly off topic i know.
Thanks for the confirmation.
Dumper 2 was brand new when I stopped working for BHP in Port Hedland, so I've lost touch with that sort of detail.
You can watch the SD70s going through dumper 4 from the sandhills on Finucane Island, so there was no question there.
I believe that four BHPB AC6000s already have the modifed engine, including 6076, the first one in bubble paint. You could tell because the turbo exhausts were still painted silver, not burnt and black.
It isn't completely an Evolution engine because it still has the water cooled intercooler and I don't know if it meets Tier 2 emissions, but it is mechanically a 16 cylinder EVO. GE sell the water cooled intercooler version for marine operation and call it the "V250" engine (250 mm bore).
I would expect that the CSX conversions are the same, so it might meet Tier 2, and the marine version certainly would, but it has unlimited supplies of water for cooling and the temperature is critical in meeting emission restrictions. But the older AC6000s might not need to meet the restrictions imposed on new locomotives anyway, although I believe there are modified standards (possibly called Tier 4) to be introduced for older units in the USA.
BHPB will really only want the AC6000s to be more reliable anyway and the newer engine might achieve that.