how do I remove the rear axle on a 1996 chevy blazer with a 4.3 and 4 wd to change the wheel seal?

The following procedure requires the use of the shift cable housing seal Installer tool No. J-33799 or equivalent.

Disconnect the battery cables (negative cable first), then remove the battery and battery tray.
Disconnect the shift cable from the vacuum actuator by disengaging the locking spring. Then push the actuator diaphragm in to release the cable.
Unlock the steering wheel at steering column so the linkage is free to move.
Raise and support the front of the truck safely using jackstands.
Remove the front wheel assemblies.
If equipped, remove the front axle skid plate.
If necessary, remove the right side caliper and support using safety wire.
Place a support under right-side lower control arm and if equipped, unload the torsion bar.
Disconnect right-side upper ball joint, then remove the support so the control arm will hang free.

To keep the axle from turning, insert a drift through the opening in the top of the brake caliper, into the corresponding vane of the brake rotor.

Matchmark the right-side drive axle to the output shaft. Remove the right-side drive axle shaft-to-tube assembly bolts and separate the drive axle from the tube assembly, then remove the drift from the brake caliper and rotor.
Unplug the 4WD indicator lamp electrical connector from the switch.
Remove the three bolts securing the cable and switch housing-to-carrier and pull the housing away to gain access to the cable locking spring. DO NOT unscrew the cable coupling nut unless the cable is being replaced.
Disconnect the cable from the shift fork shaft by lifting the spring over the slot in the shift fork.
Remove the 2 bolts securing the tube bracket to the frame.
Remove the remaining 2 upper bolts securing the tube assembly to the carrier. The other 3 were removed with the shift cable housing.
Remove the tube assembly by working around the drive axle. Be careful not to allow the sleeve, thrust washers, connector and output shaft to fall out of carrier or be damaged when removing the tube.

To install:

Apply a bead of sealant on the tube-to-carrier mating surface.
Make sure the sleeve, thrust washers, connector and output shaft are in position in the carrier. Apply grease to the thrust washer to hold it in place during assembly, then position the washer to the tube.
Install the tube and shaft assembly-to-carrier, then thread and finger-tighten a bolt at the one o'clock position but DO NOT torque. Pull the assembly down, then install the cable/switch housing and the remaining bolts. Tighten the bolts to 36 ft. lbs. (48 Nm).
Install the tube-to-frame nuts/bolts and tighten to 55 ft. lbs. (75 Nm) on 1994 models and 72 ft. lbs. (98 Nm) on 1995-99 models.
Using the hub engagement tool No. J-33798 or equivalent, check the operation of the 4WD mechanism. Insert tool into the shift fork and check for the rotation of the axle shaft.
Remove the engagement tool, then install the shift cable switch housing by pushing the cable through into fork shaft hole. The cable will automatically snap into place. Please refer to shift cable replacement, later in this section for details.
Attach the 4WD indicator light wiring connector to the switch.
Install the support under the right-side lower control arm to raise arm and connect upper ball joint. For details, please refer to of this repair guide.
Align and install right-side drive axle to the axle tube output shaft by installing one bolt first, then, rotate the axle to install and finger-tighten the remaining bolts. Tighten the bolts to 60 ft. lbs. (80 Nm).

To hold the axle from turning, insert a drift through the opening in the top of the brake caliper into the corresponding vane of the brake rotor. If the caliper was removed, either temporarily install it or use a prybar across 2 installed lug nuts.

If removed, reposition and secure the right side caliper.
If equipped, install the front axle skid plate.
Install the front wheel assemblies.
Remove the jackstands and carefully lower the vehicle.
Connect the shift cable-to-vacuum actuator by pushing the cable end into the vacuum actuator shaft hole. The cable will snap into place, automatically. For details, please refer to shift cable replacement, in this section.
Install the battery tray and battery.
Make sure the ignition is OFF , then connect the battery cables (negative cable first).