vibration

my daily mazda is stock as heck and was in fine workin order, then all of a sudden theres abit of vibration, especially in 3rd gear, guess thats like 30-40 mph, and in 5th gear theres a loud-pitched noise comin from the back of the truck when you accelerate. and i noticed leavin the taco bell drive thru tonight, there was some squeakin noise comin from the rear when i turned. maybe the rear end about to explode? could anyone fill me in on some possibilities?

Jack up back, turn wheels and shake them from side 2 side to check for play. also check yer driveshaft for play.

SOUNDS LIKE THE REAR IS GOING OUT

maybe check and see if there is any fluid in the rear end

also i hear a clunk when i downshift sometimes.

if it is making noise now its done.

Mine made a a humming sound/vibration when the axle bearing went out of it. Dump the gear oil out of the rear end and check for metallic shavings or other foregn matter. Mine had so much metal shavings in it it looked like anti seize compound. It could be something with the gears as well, I think that they are notorious for that too.

Also check the u-joints on the driveshaft like Phil said, the bearings inside the endcaps on the joints might be wore out if you got some miles on it, or if they were not greased regularly, although they might be sealed/maintenance free like the dimes?

well after spending 4 hrs taking a rear end out of one truck and putting it in this one, i had the same problem, so my pops came over, and we spent 30 min replacing a bad ujoint right after the carrier bearing

glad you got it fixed cris