I'm looking at purchasing two steering 419 axles for the extra beef, disk brakes, air lockers and the gearing will be better for on the road. My only hesitation is the brakes, I'm not super familiar with the SEE Tractor - FLU 419 ... believe they run with air assist? That may be a PIA to add to a 404 without that air system. Anybody know how that system works? Would a simple compressor & small air tank do?