Originally Posted by AJMBLAZER

One of the threads above references the NAPA GPR109 glow plug relay. This part is meant for pre-Powerstroke Ford diesels. It is $25 or so while the GPR110 which is very similar costs around $85. We're not sure what the difference is between the two but even the local NAPA couldn't tell me other than to say "$60 more". I used the 109 and so far, so good.

There are two small issues with using the NAPA Ford GPR109 relay, both of which are perfectly fixable.

1. The brackets on the stock relay are of a "north and south" orientation with one on the top and one on the bottom. The 109 has them in a sort of "north and west" orientation. All I did was put the north bracket in the stock hole and then drill a new hole below the stock lower hole to mount the west bracket with. I just couldn't turn it enough to use the stock lower hole without hitting the brake system stuff there to the right of it. Some people have reported they were able to get theirs to line up with the stock holes without trouble but I was unable to do that with mine. Might just be me.

2. The 109's larger studs use different threads than the stock relay's larger studs do. You will have to go out and find new nuts because of this. Minor but it is something to take care of before you're kneeling on the radiator shroud, stretched across the engine cussing.
The two smaller stock studs use the same thread as the 109's smaller studs so their nuts can be reused on the 109.
Note that this is for the original style relay these trucks came with from the factory. I do not know if the updated relay the military used was different.