93 7.3l club wagon where are glow plugs?

My van is hard to start at cold temps. It is -20F here today. I have a recirc pump, oil pan heater and two battery blankets on the vehicle. It also has a blanket on the hood to keep the heat in. I think my glow plugs need to be replaced. I am new to diesels. Are my glow plugs under the valve covers?

She will chug a little (like once) when I try to start her. But it is so cold I loose battery power quickly. So I keep starting over. I have a charger on the batteries.

I am thinking that the fuel is so cold that it won't ignite, and some/all the plugs are bad, compounding the problem. Is this a reasonable guess? I will replace the plugs, but I'm not quite sure where they are, as I have seen comments about them possibly being under the valve covers. Not looking foward to that in this weather, but whatever it takes........

Gotta get it goin in Alaska