How can one tell if the rear bearings are going out?

mileage... are you nearing 85k miles? That's the wear point.

Also, you can grab the tire at 12 and 6 and wiggle... if it moves, time for new bearings.

How hard are they to change on the C4 and can you recomend a brand to get?

they are not hard to change. you need a 50 torqs bit . do you have a factory service manual?? if not and you are planning on doing your own work when things come up I would invest in one .they are a wealth of info .I personally like taking the whole housing off where the bearing is located .some do them with the housing on the car

I have done a few... for me, it's easier to leave the uprights on, because otherwise, you need a vice big enough to fit...

this is also a good time to do u-joints.

Is it T50 or T55? I can't remember off hand... either way, get 2 or 3 of them, because the bolts are TIGHT and can tear up a torx bit real fast.

If you do ujoints, get an 8mm socket, 12 point, and a long 8mm box wrench to reach in there with. I also recommend new bolts and straps with the ujoints. Randy's Differential has all the parts, not the greatest price, but the selection and quality make up for it. Good stuff.

Timken is a good brand for bearings.

Make sure you have a good breaker bar or torque wrench for tightening the rear nut to approximately 200 ft lbs.

Get the new Teflon washer from the GM dealer when you do it, too.

Timken or SKF.

Both are available at Rockauto.com for about the same $ - $126.00 or so.

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