Not sure about the back, but the speaker size in the front for the ones that are fitted as standard is 5x7. I'd imagine therefore that any that size will swap no probs.
Quote: ouch quite steep! what headunit are you running them with?
sony cdx gt828u its not a dear one but i like it. and yes that is really bloody steep when i have just found them for 34 pound s**t going to phone them up and tell them to poke there speakers im glad i only put a 20 pound deposit down