What Kind of Geep is This?

Saw this at South Station Today.
Geep What?


I like the horn array:


High Nose End:

 

GP18, judging by the style of radiators. The 4 stacks are non-standard.

 

mbta 904

Said here (in old paint) http://photos.nerail.org/showpic/?2...=SIMPLE&PAGE=3&BOOL=ALL&SEARCHSTRING=mbta+904 It says it is a GP-9 rebuilt into a GP-18 which makes sense because i recall the mbta using gp9 work engines

 

Thanks guys!
That makes sense since they are doing track work in the area.