Need wiring diagram from alpinecde 9852 to 98 gmc sierra

The simplest solution to this is to use an after market harness like this. They're available at most big box electronics stores like BestBuy. The colors on this should match the colors on the Alpine so it's as simple as matching them up and soldering them together. The important colors are those for the constant and switched power (usually yellow and red), ground (black), and the speakers pairs (purple, green, white and grey). The dimmer (orange) and remote (blue) or not necessary to normal operation.

The factory wiring colors are shown here in case you don't want to use the harness. All you need to do is match the descriptions and connect the wires.

Hope this helps. Let me know if you have any questions.

Ray