If I were doing it over again, I would definitely just go with TheNeek's adapters since you they allow you to fit 5 1/4" speakers. With few exceptions the 5-1/4"s are going to sound better than 4"s.
FWIW or for anyone using the search feature down the road: Retro Sounds makes 4" speakers that fit behind the stock door grilles. You can find them at Crutchfield and I think they sound very good considering their size. They are the appropriate depth but I had to make my own crude adapters out of plexi-glass to match up the factory mounting hole pattern in the door to the new speaker mounting hole pattern. It was 3 vs. 4 holes IIRC and you could just drill new holes in to the door sheet metal, but I didn't want to do that so that's why I made some simple adapters.
FWIW or for anyone using the search feature down the road: Retro Sounds makes 4" speakers that fit behind the stock door grilles. You can find them at Crutchfield and I think they sound very good considering their size. They are the appropriate depth but I had to make my own crude adapters out of plexi-glass to match up the factory mounting hole pattern in the door to the new speaker mounting hole pattern. It was 3 vs. 4 holes IIRC and you could just drill new holes in to the door sheet metal, but I didn't want to do that so that's why I made some simple adapters.
