I have just repaired the open wire feeds on the front offside speaker itself. There are two connectors one for the tweeter and one the mid range (can't really call it bass) speakers. The crossover must be in the wiring somewhere?
So am I right in thinking you wire the existing cables for both speakers into the crossover and then new cable to the new tweeter and speaker?
Or rip out old wiring and start again as it has inline crossover?
The original setup does not have proper crossovers, just a capacitor on the tweeter.
When you get you new set simply use the existing speaker wire in the door to feed the crossover.
(One crossover for each side)
There will be outputs on the crossover for the tweeter and woofer. Hide the crosover behind the door card, warp in bubble wrap to stop it banging around.
The tweeters are easy to replace, I had to englarge the hole in the door card slightly using a Dremmel with an emery cloth wheel, very easy. I ueda gluegun to glue the new tweeter in place.
Fitting the 17cm woofers with spacers is relatively easy too.