Like Spazz said, they are something like 4" speakers (some metric variation from standard)... to squeeze even a pair of 5¼" speakers requires that you cut the speaker mounting brackets AND some of the sheet metal behind the speaker. Otherwise, you are stuck with some very little speakers... then again, rear-fill is best anyway... don't need a ton of sound from the rear stage to sound good. Good Luck!

Coach... I mean Randy (I often forget who I really am)

Undergoing LS1 Conversion as we speak!
Click Image to Visit My Website!
My Webshots Gallery...