glow plug problems?

[5.0bronco]

im looking at trading my 97 for a 85 f-250 ex-cab 4x4 4 speed. the truck looks really clean from the pictures but i havent seen it in person yet, the guy says the truck is having glow plug issues. the guy said he put new glow plugs and relay on the truck, he said they worked for a while then quit working, he says the wait to start light comes on still and he said he put the glow plugs in it from ford but i dont know. does any one have any clue what could be the problem? im thinking he got the cheap glow plugs and put them in it

 

[Andylad13]

I've had a resistor go bad before believe it or not. One day the gp wires show 10V to the plug, the next day they show 12.4V. If that's the case, I would make sure that all the plugs come out easy and no tips have broken off. If they do, and this truck is what you want, then you can go through the gp system and get everything working again for probably $300.