Ford

I was driving my van on saturday. once i got home i parked it and a couple of hours later i decide to go to the store. once i started it, i noticed a high pitched grind sound coming from the rear end. i know this van is rwd hence could the problem be the differential? driveshaft? rear struts? what can this be? it is my daily driver and for the past week it is been extremely subtlely making the sound as soon as i drove away. but this weekend it got extremely loud. any solutions or can you identify the problem?thanks

It is probably the rear brakes, it is probably time for new ones, make sure the parking brake is off all the way.