replacing front main crank seal?
 

Can anyone tell me if the front main bearing seal can be replaced on 2000 4wd s-10 blazer (4.3 vortec) , without pulling motor. Is there a front main seal, or is there just a oil pan gasket?

I assume you're referring to the front crankshaft seal? This can be replaced without removing the engine. It is located in the timing chain cover. Most of the accessories on the front of the engine must be removed (alternator, pumps, damper etc...) I believe the seal can be changed without removing the timing chain cover.

Once you remove the radiator shrouds (top & bottom - you may also have to remove the fan to get the bottom shroud out); you only have to pull the serpentine belt off and then you remove the crank pulley/balancer. No other accessories need to be removed. If you suspect a front seal leak, check the crank pulley/balancer for wear. The lip seal can wear a groove in the balancer which can make a new seal leak.

Wear Sleeve
 

Just a note here, if your balancer pulley happens to be grooved they have wear sleeves available at your local parts store to repair the damage. Very cheap and easy to install.

I just put a new balancer on mine for like 60 bucks. This is a REALLY old thread, though, so I doubt the OP cares much at this point.

Maybe old but still could be a refresher for someone needing. Thanks to the knowledgeable responses though.

I sold my ZR2 four years ago but still read here 5 times or more a week. Just maybe I'll have something that might help someone.