If the noise is directly behind the shafts the problem is most likely in the differential. Check to see if any part of the c/v shaft is turning. If only the inner part of the shaft is turning the shaft is probably broken.
check the drive axles they could be bad
countershaft bearing could be problem
This is a manual transmission car, I presume. If it's an auto, you have a big problem! Grinding could mean that something inside the transmission is failing. Or it could mean that your transmission fluid is low. OR, it could mean that your clutch is worn or is out of adjustment. Grinding usually means that the clutch is not disengaging properly when you push the clutch pedal, or perhaps, a synchronizer has failed. Whatever the case, If I were you, I'd get the car to my mechanic and have her looked at.
IT could be a faulty transmission or the belt could be grinding up against an unknown source. = )
If you aren't moving and it is making the noise, it may be the transmission or engine. if you are moving and it makes it, it could be a joint or a worn disc brake. If you aren't moving it is definitely not a joint.
there is more then one speed sensor i know there is one in the transmission and one around the front axles and one more not to sure where it could be
This could be your clutch pressure plate is worne..
check CV joints, if bad replace shafts and joints assembly
HeyJoe==They are not cleanable. If it is grinding between gears, the synchronizers need replacing. GoodluckJoe
sounds transmission related or possable flywheel related That would be the power headlight motor!!
If it just lasts for 1 or 2 seconds, it is the clutch plates ratteling and not to worry.
Front grinding could be a bad wheel bearing or in the front axle assembly.