Reliance 606 Water Heater Pilot Light. Burner shuts down, that is a different problem and not a thermocouple one. They don't cost much and no special tools required.
They are relatively small units that provide hot water on demand. Water heater shutdown relight and maintenance you. If it’s igniting, replace the reliance water heater thermostat or gas control valve.
96 S10 Heater Core Replacement. Remove the screws that hold the heater core straps and the bracket over the heater core tubes. When it happens, you won't need to pay.
If one of the hoses is hot, and the other one is cold, that is a pretty good indication that the heater core is clogged. Loosen the retainers and remove the heater core retaining straps. Pull the heater core out of the housing.