67-72 am/fm wiring help

[briank]

Just purchased an original 67-72 am/fm truck radio and am planning to install in my '68. The back of the radio has a place to plug a connector in to it but I do not have that connector as my truck previously had an aftermarket spliced in. So what wires go where? Gotta be pretty simple as there is only speaker wires, power and an antenna but I don't want to mess up the radio. So which prong on the connector does each wire attch to? Thanks, Brian