Here's a generic exploded view of a rear brake. Doesn't show Wheel Cylinder, Brake Hose or Parking Brake Cable.
E350 uses a "full floating" rear axle design. To get the drum off, you have to remove axle, lose oil, and dismantle bearings. Re-assembly requires new seals and a precision bearing adjustment. Not for the inexperienced!
Here's the front, again generic. Does NOT show the Hose or ABS Sensor.
You can get the caliper and pads off without disturbing the bearings or removing the rotor. Removing rotor involves bearings, seals, adjustments, like the rear. Also, the bolts holding a bracket that has to come off to remove the rotor are very big and very tight.
OP's that live up in your wet area say the rainwater dripping off the roof splashes into the front brakes and rusts them. Makes sense. I can say I worked on one that was stored near salt water. Had to knock the calipers off the rotors with a hand sledge (once the fasteners were out!!!) and then pound the pads out of the calipers. The friction part of the pads came off in pieces. But... the coach was still moving and would actually stop to an extent...
