Connecting my Delco AM/FM to Amp

[ShortHaul]

Hey all. Im seeking some assistance in connecting my original Delco AM/FM radio in my 75 C20 to an Amp.

Specs are as follows

Vehicle: 1975 Chevrolet C20
Radio: Delco AM/FM
Amp: Infinity Kappa K4

The amp has has RCA Input ports, LF, RF, LR, RR. It comes with Speaker wire to RCA adapters for just this type of connection.

Amp
Kappa amp back by awesome_adawson, on Flickr

Connectors
amp connections by awesome_adawson, on Flickr

The AM/FM features the following speaker outputs.
Untitled by awesome_adawson, on Flickr

According to this diagram they should correspond with these.

RadioPlugsDiagram_3 by awesome_adawson, on Flickr


My truck only had the Single speaker in the dash, but the radio output has the provisions for the connections labeled H,J,K on the diagram, I just have to add wire.

When I bought it, the truck had two house type speakers (like you'd see on a cheap boombox) wired behind the seat to the connector shown above. (labeled ABCD)

The amp is powering 2 6x9's and 2 3.5"s now, and is bluetooth connected, but I still want to be able to use the stock radio.

My question is, quite simply, which wires to connect, in what order, to which input on the amp. Thank you!