Tater, it's not too terribly difficult to install a head unit. Basically, you need to take your stock out, if its the pioneer 6 disc, youll need the 4 prong tool, what you can do is take it to a local car audio shop and they can take it out for you. After that, you need to buy a wiring harness that will connect the stock wires inside the truck to the new head unit. this might involve cutting and splicing some wires...as for filling in the extra space, when you buy the wiring harness you will also need to buy a head unit car kit for the vehicle. this is typically a plastic pieve that has a space for the new head unit, but also has something to fill in the extra space from the stock head unit. this could be a slot inside where u can put cds or something like that. the wiring harness should run you about $10-15 and another $10-15 for the kit. any car audio shop or circuit city or best buy type of place would have them in stock. I had my head unit installed because the place i bought it has a deal that if its bought there they install for only $1. i couldnt beat that, but i've done many other cars and its not hard
Good luck!
thanks
andy