I took the MOV off the speedo circuit board last night so I can put the speedo back in the truck temporarily on Saturday and see if fuse #25 blows. I expect that it won't since I determined that the gauge cluster was shorted by removing things on the circuit one at a time and I found my short in the last cluster which was the last item removed. I spent a ridiculous amount of time looking for a suitable replacement MOV and found a couple of "candidates" that I think will work.
I'll post that info after I get a successful re-install of the gauge cluster. I have two MOV's picked out. One is better than the original in durability and the other is pretty close to the original. This is all based on reading peoples posts on the internet (other sites) and some guesswork.
The MOV can take a certain amount of voltage spike pulse for a certain number of times so more than one MOV would work. The one ford put in is the cheaper option. It only takes a hit from a spike a few times. By spending a little more you can get one that takes 5 times the hits before it completely fails. The extra cost is around a quarter. I think the more durable one is the better choice but I'm not sure, though. The cheaper one does its job a few times and then fails completely. The more durable one does its job more times and then fails completely. Its like a cheap power strip surge protector as opposed to an expensive power strip surge protector. Do you guys think there is any benefit from only being able to work for a couple of surges?