I need help on how to replace the heating coil on my friends 1985 GMC truck. I would like to find a maintainence book or a step by step web site, but I haven't been able to find anything yet. If anyone knows where I can go to get the hook up let me know.

Heating coil??
You mean for the electric choke heater?

Or do you mean heater core, (for the ventilation system)?

The ventilation heater core. Sorry for mistermage but I'm kind of a third wheel on this one, never had to due this kind of maitainence before.

The ventilation heater core. Sorry for mistermage but I'm kind of a third wheel on this one, never had to due this kind of maitainence before.
Try a Haynes or Chiltons service manual for this truck. Both provide detailed step-by-step instructions for this repair. The manuals are sold at many auto parts stores, or your local library may have one, or go here:
http://www.nextag.com/chevrolet-shop-manual/search-html