RC2018

I would suggest you take a hard look at the headlight dimmer switch. To simplify the headlight circuit, headlight switch feeds power to dimmer that feed lightbulbs, hi or low depending on the setting. Since your hi beams are ok, I think maybe the dimmer switch may be failing.

I replaced mine on my 2003 Diplomat. I replaced mine with Silicone hose. The metal you are referring to between the rubber on mine has a muffler clamp welded to a strap supporting it and after jiggling it around during hose replacement it started leaking at the clamp from the rust. The rest of the metal pipe was fine but there were pin holes in the metal pipe where the clamp was attached. I had to send the metal pipes to a fab shop to duplicate, (no part number or drawing that I could find) I replaced with custom fabricated Stainless Steel pipes. The rubber hoses I took off were hard and cracked. In the end I replaced all the coolant hoses with silicone. If yo use silicone, remember they require a specific style clamp made for soft hose.

My 2003 DIPLOMAT 8.3 TOOK MAIN BELT TENSIONER # 5259022. MAIN SERPENTINE BELT; DAYCO # 3289235 AC BELT; GATES # XL 11A1170