Hey,
We have (what I think is) an original 404 air compressor kicking about somewhere. We eventually decided we didn't want to have something uneccesary spinning all the time, and got a 24V electric one from a fire appliance. Which we've not got round to fitting.
It goes to the left of the engine (looking from the front), slightly further out from the genny/alternator.
Happy to send you a picture, and could be talked into selling it as we're unlikely to use it.