I have a 1994 f150 5.0 engine and automatic transmission. Problem I am having is speedometer, cruise control is not working. Overdrive light is flashing and number 18 fuse keep blowing Thank for any help horn is still working

 

Fuse 18 feeds the speedometer. There is also a POSM module up there with it that takes the speed sensor signal and conditions it, and sends it to everyone else that needs it, which would be the ECM for the transmission, and the cruise.

Look at the last page on the diagram in this link.
http://www.revbase.com/BBBMotor/Wd/DownloadPdf?id=4921

1st thing I would do is unplug the wiring from the speed sensor behind the cluster and then try another fuse. If the fuse is ok with the sensor wiring unplugged, I would trace this wiring back along the frame to the rearend. It may be damaged somewhere.