Do i need the prop valve senser it is leaking on my truck and i wonder if i can just put a plug in it or do i need to replace the whole prop valve

 

That sensor is needed.
It is the pressure differential switch, which is used to sense a pressure difference between the front and rear brakes (ie. fluid leak), and illuminates the "Brake" light on the instrument panel.

 

well where would be the best place to buy a new prop valve then

 

Dealer might be your only bet or junkyard. I did a quick search on www.autozone.com and www.napaonline.com and didn't get anything.

Here is a copy and paste from the parts manual. I don't remember what truck you got this is for 94-96 2wd. I'm sure its the same all years and 4wd also, but not sure about 4wheel abs.

 

im going to try some junkyards its a 89 2wd