By the way, if you bottom-mount 6x9s through smaller holes, the speakers' surrounds will likely hit the metal package tray and muddy the sound due to restricted cone movement.
of which i have 2 of..one i "think" iso ut of a b or c body..the other one eledgadly was from an A but it looks EXACTLY the same...id probably have to dig a bit but ive got the switches for them tooSeveral companies still make the dual-pattern 5x7/6x8 speakers. I have a brand new set in the box in my spare room... well, they've never been out of the box, but I've had them for about 6 years now. :-D As I recall, the '68-'74 B-cars have one 6x9 hole and one 5x7. One was actually for rear-defog-equipped cars as an intake from the interior. They were never available with dual rear speakers.
ihave a mess of 4spd stuff....