All rash decisions -
How sure are you it's the rear?
Have someone stand next to it while you turn to listen.
If it is the rear, jack up one rear wheel - trans in neutral. Spin the wheel by hand,
You should be able to hear it crunching and binding if it is the spyders.
But sounds can be very deceiving, look at the front axle u-joints for loose caps, or rust particles coming out. Jacking up the wheels could also help.