I changed mine one year back, no play in bearing, only terrible noise. Reason was that water had gotten in the bearing. Very rusty and some quite deep grooves on the braring surfaces. The job is not that bad, you just have to have right attitude and some special/homemade tools to extract the outer piece of the bearing. Here is a quick how-to, someone posted even pics when I was asking for advice:
- remove wheel, brake caliper and disk
- undo the bolts from drive shaft flange and support the saft properly
- undo the big nut from the inside of the hub, this can be tight
- flange for drive shaft should come out quite easy
- the shaft that goes through the hub will come off with two long bolts (M12x1,5 IIRC, someone shoud confirm this) screwed through the wheel bolt holes. Put some metal under the long bolt ends that face the brake shield
- remainings of the bearing stuck on the shaft, normal puller will do this
- now you need the homemade tools: one flange that fits inside the hub and on the outer ring of bearing with a hole for a bolt in the middle. Put this on the rear side. On the outside you need a "pipe" that faces the outer dia of the hub and the bearing fits inside. And again a flange with a hole...then you simply turn the nuts on the bolt and voila, the bearing is off.
- assembly is reverse of this, but you need to put the new bearing to freezer, then put it in. Then let it warm and meanwhile freeze the hub shaft, it should then go in quite easily.
- torque for the big nut was 300 Nm (IIRC, someone could confirm) and the flange bolts were "not that tight"...
Hope this helps, many people, even at the llocal Opel-shop say that its a real PITA but I was surprized how easy and straight forward it was (after I found the correct "homemade tools"