1996 F250 Cold Start Problem

[Coalrollar58]

My buddy just picked up this truck and we are trying to diagnose the problem that it has while trying to start in the cold. We have checked the GP and they all ohm out. We have also put in a brand new GPR. In addition all the fuses are good. I have read about a Glow Plug Relay Controller but i dont know much about them or where it is located on the motor. Could someone give me some help and let me know more about this Glow Plug Relay Controller and the how hard it would be to change. Thanks.