Glow plugs and maintenance...
I have an '02 F-350 dually with about 90k on it. I use it mostly for towing a horse trailer and when the weather is crappy. I have an Edge programmer set to tow mode, a 4" exhaust, and modified the intake to run a canister filter. I just replaced the original batteries after a few no-start issues last winter due to dead batteries after really cold weather and days on end without use, and all the original shocks. Leasing cars the past decade has made me really lax about staying on top the trucks maintenance.
My question is about glow plugs, are there aftermarket plugs that make a difference in performance or fuel economy like are available for gasoline engines? How often should they be replaced for routine maintenance?