See if this helps.
See Figures 9 through 14
Fig. 9: Make sure the marks camshaft and crankshaft sprockets are aligned
Fig. 10: Unfasten the camshaft sprocket retainers
Fig. 11: Remove the camshaft sprocket and the timing chain together
Fig. 12: Using a suitable puller, remove the crankshaft sprocket
The following procedure requires the use of the Crankshaft Sprocket Removal tool No. J-5825-A or equivalent, and the Crankshaft Sprocket Installation tool No. J-5590 or equivalent.
Remove the timing cover from the engine.
Rotate the crankshaft until the No. 4 cylinder is on the TDC of its compression stroke and the camshaft sprocket mark aligns with the mark on the crankshaft sprocket (facing each other at a point closest together in their travel) and in line with the shaft centers.
If applicable, remove the crankshaft position sensor reluctor ring.
Fig. 13: Timing mark alignment-4.3L engine
Remove the camshaft sprocket-to-camshaft nut and/or bolts, then remove the camshaft sprocket (along with the timing chain). If the sprocket is difficult to remove, use a plastic mallet to bump the sprocket from the camshaft.
The camshaft sprocket (located by a dowel) is lightly pressed onto the camshaft and should come off easily. The chain comes off with the camshaft sprocket.
If necessary use J-5825-A or an equivalent crankshaft sprocket removal tool to free the timing sprocket from the crankshaft.
If necessary, remove the crankshaft sprocket key.
Inspect the timing chain and the timing sprockets for wear or damage, replace the damaged parts as necessary.
Fig. 14: Removal (top) and installation of the crankshaft timing gear
Using a putty knife, clean the gasket mounting surfaces. Using solvent, clean the oil and grease from the gasket mounting surfaces.
If removed, install the crankshaft sprocket key.
If removed, use J-5590, or an equivalent crankshaft sprocket installation tool and a hammer to drive the crankshaft sprocket onto the crankshaft, without disturbing the position of the engine.
During installation, coat the thrust surfaces lightly with Molykote® or an equivalent pre-lube.
Position the timing chain over the camshaft sprocket. Arrange the camshaft sprocket in such a way that the timing marks will align between the shaft centers and the camshaft locating dowel will enter the dowel hole in the cam sprocket.
Position the chain under the crankshaft sprocket, then place the cam sprocket, with the chain still mounted over it, in position on the front of the camshaft. Install and tighten the camshaft sprocket-to-camshaft retainers to 21 ft. lbs. (28 Nm) on 1994-96 models and 18 ft. lbs. (25 Nm) on 1997-99 models.
With the timing chain installed, turn the crankshaft two complete revolutions, then check to make certain that the timing marks are in correct alignment between the shaft centers.
If applicable, install the crankshaft position sensor reluctor ring.
Install the timing cover.