The crop to the left is of the area to the right of the driver's instrument panel. When Class 37s were dual braked there was a need to add another gauge to the panel (the auto-air brake pipe gauge) so the main reservoir gauge was relocated. It was put in one of two places, either to the right of the master controller or to the right of the existing instrument panel. One would have been easy requiring the addition of a pre-fabricated box with a bit of external pipework and one would have been a pain in the arse involving cutting a new hole in the bulkhead and burying the pipework under the desk. We had the latter and we have removed it - an equal pain to installing it in the first place - and welded a new piece of steel into fill the hole.
Compare this crop to the photo above to see the changes.