Ive just bought a new pair of kenwood 6" speakers, with tweeters and crossovers. a friends going to mount them in custom pods in the doors for me.
I have kenwood 7x10's in the rear in the wheel recesses but im going to pull them i think.
re: the speakers below the 1/4 window panel, one of the guys at 924.org did an extremely well put together guide for doing a swap:
rear panel without touching window! step-by-step [pics]