A bit of history on these units (WC 6900-6949)
Originally CN SD40's in the 5000-5240 series, look like this:
http://www.railroadforums.com/photos/showphoto.php?photo=16213
- rebuild by Ashtom in 1997/1998, look like this:
http://www.railroadforums.com/photos/showphoto.php?photo=24256
First leased, then bought by CN, who gave them this WC patch jobs. Funny thing is, its "foreign power", even though the the unit has been riding the Canadian Transcon since the 60s!
While in GCFX sheme they used to be pretty common around here, now they're mostly in the US. I guess surplus BCOL power, Dash 9's, Dash 8's and SD40-2's, has replaced them.
Interstingly it was trailing CN 5241, CN's oldest SD40-2(W) of 30 years old.