I dont have one but here is what you need.

If any one on this BBS has one maybe they can print the diagram from for you. Otherwise you might consider buying this. If you are planning to keep your truck for a while and do a lot of your own work on it is well worth the price. Every car I have ever owned I got the service manual for and it has always been worth it.

I am just finishing the install of an Empeg into my 1994 Cadilllac Deville Concours. I am using the Empeg as a second head unit and have the factory head unit tied in through the aux input of the Empeg. All of this is then fed into a couple of amplifiers in the trunk. There is no way I could have accomplished this integration without the factory service manual. And you can forget about getting anyone else to help sort out this kind of thing except in maybe a very high end car audio shop. Then you will spend much more than the cost of the manual.

Anyways, that is my 2¢ worth.