A 69 built with a factory stereo will have 4 speakers; one in eack kick panel and two mounted on the package shelf. The front speaker mounting is depicted on page A3 section U79 of the Assembly Instruction Manual [AIM].
A rear defogger was a factory or dealer-installed option; GMPD sold a kit for dealers to install. The mounting of the switch can be found in the AIM on page A1 section C50. Fisher Body must have installed the wiring, unit and grille as that is not in the AIM.