Another "what is it"??

[Oonrahnjay]

    This is from an '03 Gillig "low floor".  I'm thinking it's a heat exchanger for the separating the engine coolant (or "warmant") from the interior OTR heating system circuit.  But IDK ...
    Info, please?   Thx,   BH 

[gumpy]

I think you nailed it!

[Oonrahnjay]

I think you nailed it! 

      Thanks.  There is also another item off the "donor" bus -- a circulation pump about the size of a 2-liter soda bottle.  Gonna be warm in the big bus when we're finished!