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2011 Onstar only antenna. Want to add XM

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Hi thanks for taking the time to read....I've spent all day trying to find an answer but each step it seems there's so many different ways .


I have a 2011 Silverado, it has the shark fin antenna. when i pulled the head liner down, the antenna only has one wire. The truck came with Onstar so I'm assuming its for that only.

The truck does not have the factory xm tuner behind the glove box.


I'm planning on purchasing the Onyx ez xm kit so if i ever buy a new vehicle i can install it there, but i don't want to use the magnetic antenna and would like to keep the stock look.

I contacted a gm parts supplier and they said the Antenna i need would be PN#20791465 which instead of have 1 wire has 2 wires.

Suggested antenna


My issue now is that because the antenna has a plug with 2 wires, do I need a new harness that has to 2 wire connection plug that has a plug for the onstar and xm tuner?

Is there a sort of Y splitter that i can plug into the new antenna which will then allow the existing onstar plug to plug into the new antenna, and then run a separate xm cable from the  new antenna to xm tuner? I can't seem to find any part numbers or any solutions anywhere.


Some posts mention an antenna with a 3 wire plug or an antenna with 3 wires but 2 plugs , one 2 prong plug which i assume if for onstar and gps and then a separate xm plug.


There's also a XM only antenna but i don't want to get rid of the onstar option.


any help would be appreciated 


One site has 2 harnesses shown but i don't  know which would work?


It's all very confusing.


#2 is the antenna cables shown in diagram

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