I actually based this (believe it or not!) on a pic of a Norfolk Southern GE Dash-9 or AC 6000 but at the time didn't have the know-how to replicate the wide nose, so this ended up with a standard narrow nose. Since then, after researching more pictures, I reckon is must be a Dash-8 (it seems pretty close to me, anyway).
This bad boy is 44 studs long - probably bigger than I'll ever attempt again simply due to the quantity of bricks required - never thought I'd run short of black!
I gave this one triple-bogies - looks the goods, but without some clever truck-work, it scrapes badly around curves.