Couple of days ago i started the truck and when i started to drive the speedo was not working and when it shifted into 2 or 3rd the o/d light started to flash it shifts smooth. So did alot of research and people said to change the abs/vss on the diff so i did that nothing happened. Do you guys think i should change the oss which is 50 bucks from ford part# F81Z-7M101-AA. Also 2 days ago randomly the speedo worked and o/d light stopped flashing and i thought everything was fine then it happened again. I need some help guys.