The Pontiac uses a permanently sealed double race ball bearing type bearing. The MB uses a tapered roller bearing packed with high melting point grease. There is a little more rolling resistance with the double taper roller bearing, so the wheel won't spin as long.

You should have just palpable play -- too little for a distinct "thump" when you pull the wheel straight out and push straight back in. To set the clearance, take the hub cover off with a large pair of channellocks, loosen the locking screw, turn the nut in until the wheel turns only with considerable resistance (don't tighten the nut down untill the wheel is really hard to turn!), then back off 1/3 turn on the nut and tighten the locking screw. Re-install the hub cover with a driver on the lip -- DO NOT drive it on by thumping the center with a mallet or hammer -- this will cause the outer part to bulge and draw the opening closed, so that it won't stay tight anymore. Sounds counter intuitive, but banging on the center makes them loose every time.

The nice thing about the GM bearings is that they are all the same on all four wheels, held on by four bolts. Easy to change, not adjustable (so the can't be adjusted wrong), last many many miles, have the spline for the front drive axle, so one bearing fits both front and read. The bad thing is that they cost about $90 each, last time I bought one!

Peter

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1972 220D ?? miles
1988 300E 200,012
1987 300D Turbo killed 9/25/07, 275,000 miles
1985 Volvo 740 GLE Turobodiesel 218,000
1972 280 SE 4.5 165, 000 - It runs!