i'm looking for a steering wheel with wood grain for my 04 ls as well. you can get the part number from the lincoln dealer; that's how i got it. apparently, according to the dealer, there are different steering wheels that pair up with the different options as far as radio goes. so you need to find one that matches your car.
i know very little and i'm going by what i heard, so i could be wrong. but you can get the part number from the dealer. have your VIN handy when you call.