The best thing to do is to remove the door panel and the speaker and measure the opening. Roll the window all the way down and measure the distance from the mounting area to where the shallowest point is inside the door, like the window or track. The speaker size and mounting depth will dictate what speakers you can use without any modifications. "Will fit with bracket" usually applies to when you have a 6x9 speaker for instance, and the recommended replacement is a 6.5 speaker. The bracket allows the 6.5 to be installing in that larger opening. The reason this is recommended is that you can not always install an aftermarket 6x9 in a factory location without installing spacers due to mounting depth differences.