This is the 2nd time in 1 month the speedometer just stopped at 70MPH and would only drop down to 40MPH with the key off. I have found that a clear fuses under the steering wheel, one of them blew. It was for the trailer charging system. I still have not replalced it, but the first time this happened it was night time and I saw a flash from under the dash and thats when my speedo went haywire. I found that fuse so I decided to check the 10 amp and 15 amp regular fuses next to it and as soon as i pulled out the second one down from the top (dont remember the number right now) All my gages started flickering back and forth for about 5 seconds then all of them stopped and the speedo was working fine. So. today it happened again and I did the same thing to the 15 amp fuse and its fine, but I never replced the clear cartridge fuse for the charging system, so what could it be? Is this a common probelm with the F-350's because i did a search and its only 150's I found... help.