Hi my 1997 f-150 4.6 , the speedo stop working and the O/D light started blinking what can it be.....

 

i think on our trucks the speedo is on the rear diff. im not 100% sure. if the OD light is flashing it should have a code a code reader from autozone or a tranny shop should be able to read it. when my speedo went out i just kept driving because i know the tone of my truck at the speeds i was on the expressway it went to 20 then 0 then 90 thne 73mph and its worked fine since the. get a code read and see what the OD code is.

 

Speed sensor on the tranny (or transfer case if 4x4) would be the first usual suspect.

Adrianspeeder