ok i know im a noob to this forums but i've been reading on here that there seems to be alot of threads about the fuse blowing out most of the time...well i've been working on this ford's alot but usaully what happens is on the right side runs a harness that goes to the transmission and up to where almost the seloind is at which is being hold together by a 10mm bolt but anywho what causes the short is that since its running close to the header it gets cought by the heat sheild and ends up melting and melting some other wires in between and gets it grounded so which causes the fuse number #21 to blow..out the best way to check if this a cause to your problem turn the tire to the left and you can see the end of the header and the harness right over it..so just kinda move it up to see if its melts or burned up..but be sure you let your engine cool down you dont wanna get burned up yourself too..and once you find if thats your problem you would have to unplug the plugs from the transmission which is a total of 5 plugs on the transmission i dont know about the 4x4..and unbolt the 10mm from the top which i said earlier pull the whole harness to the top..to fix your wires cause its a PITA to fix it while its still in the truck you have very limited space to work with..once your done put it back and its should be the problem..and if ain't it could be something esle in that matter..i hope this helps anyone on here.. GOOD LUCK TO ALL