How to replace distributor on 1989 gmc 1500 4x4 ?

Distributor

REMOVAL

See Figures 1, 2, 3 and 4

1. Disconnect the negative battery cable.
2. Tag and remove the spark plug wires and the coil leads from the distributor.
3. Unplug the electrical connector at the base of the distributor.

Fig. Fig. 1: Mark the distributor and tag the spark plug wires

Fig. Fig. 2: A distributor wrench can be used to loosen hold-down bolt

4. Loosen the distributor cap fasteners and remove the cap.
5. Using a marker, matchmark the rotor-to-housing and housing-to-engine block positions so that they can be matched during installation.
6. Loosen and remove the distributor hold-down bolt and clamp.
7. Remove the distributor from the engine.

Fig. Fig. 3: Remove the distributor hold-down bolt and clamp

Fig. Fig. 4: Be sure to mark the distributor position before removing it

INSTALLATION

Engine Not Disturbed

1. Install the distributor in the engine making sure that the matchmarks are properly aligned.
2. If the rotor-to-housing and housing-to-engine marks are not aligned, the distributor gear may be off a tooth or more. If this is the case repeat the installation process until the marks are perfectly aligned.
3. Install the hold-down clamp and bolt, then tighten the bolt to 20 ft. lbs. (27 Nm).
4. Install the distributor cap and attach the electrical connector at the base of the distributor.
5. Attach the spark plug wires and coil leads.
6. Connect the negative battery cable.

Engine Disturbed

1. Remove the No. 1 cylinder spark plug.
2. Turn the engine using a socket wrench on the large bolt on the front of the crankshaft pulley. Place a finger near the No. 1 spark plug hole and turn the crankshaft until the piston reaches Top Dead Center (TDC). As the engine approaches TDC, you will feel air being expelled by the No. 1 cylinder. If the position is not being met, turn the engine another full turn (360 degree). Once the engine's position is correct, install the spark plug.
3. Align the pre-drilled indent hole in the distributor driven gear with the white painted alignment line on the lower portion of the shaft housing.
4. Using a long screwdriver, align the oil pump drive shaft in the engine in the mating drive tab in the distributor.
5. Install the distributor in the engine.
6. When the distributor is fully seated, the rotor segment should be aligned with the pointer cast in the distributor base. The pointer will have a "6" or "8" cast into it indicating a 6 or 8-cylinder engine. If the rotor segment is not within a few degrees of the pointer, the distributor gear may be off a tooth or more. If this is the case repeat the process until the rotor aligns with the pointer.
7. Install the cap and fasten the mounting screws.
8. Install the hold-down clamp and bolt, then tighten the bolt to 20 ft. lbs. (27 Nm).
9. Engage the electrical connections and the spark plug wires.