Saw something similar down here in the valley not long back.

The South African Cat dealer Barlow has done quite a lot of conversions for underground machines, including graders and dozers. They told me there's a lot to it, not just lowering the cab. All the electrics and hydrualics have to meet underground safety regulations and that can be time consuming. And yes, a few months underground and a few strikes against the tunnel sides and even a new machine can look like it's pretty old.

@ Rowan: I design the cabin, it has full FOPS certification. The roof plate is 20 mm (3/4”) thick to limited impact deflection in the event of a cave-in. It also has a 75mm (3”) heavy wall pipe extending out the side to help protect the cabin from wall impacts. It’s a lot different in concept to a traditional grader cabin. All grader cabins have a front windscreen that slops forward for better visibility and so the dust doesn’t hang on it. The problem underground is the drives are curved in the corners and if the windscreen was to sloop forward in makes the doors winder at the top. By slopping the window back it makes the doors narrower at the top therefore they are less susceptible to damage and makes it easier to get out in a hurry. The driver actual sits on the original cabin floor with his legs straddling either side of the main frame.

@MJW: there is more work in reconfiguring the grader controls that making the cabin. Every thing has to be relocated. In this case we even had to shorten the blade lift cylinders buy about 60 mm so they would clear.