okay smaller plug at the back of the radio. Pin H DK GRN/WHT remote play back right audio signal. Pin J BRN/WHT remote play back left audio. Pin K BLK/WHT remote play back device common audio signal. You may or may not have the wires already there in the plug. My guess is that you do. I don't think they would make one plug for on star and one for on star and XM. I tend to believe you have the plug or you don't. Have your read the write up about which wires to plug/ tap into with XM? there are a few write ups on it.
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