Does anyone know a source for parts and information on servicing for a 48 yr. old Sears floor furnace? The sears website was no help.

Many operating parts like gas valves/pilots/thermocouples/milivolt generators/safety limit controls can be replaced with over the counter style parts. These parts might look different or have a different part number but will function just like the original. Your best bet on these parts are to visit a Grainger or a HVAC parts supply house. These parts will need to be matched up to the originals for operating voltage and setting like temperature Etc.