My panel did not come with XM, that's why I want to install it. I've researched this and talked to a few people who have added XM to an "XM ready" stock radio. From what I've learned you need to have code UE1 to be able to add the XM module, and I have that code.

The link you posted is one of the ones read. I also got a lot of information from this article
https://www.global-auto-tech.com/services/xm/

And this page starting at post# 11
https://www.corvetteforum.com/forums...-resolved.html
Thanks again.

 

This is the wiring diagram the connectors on the head unit are X1 and X2 the pin numbers are noted.

 

For what it's worth, I "fixed" a couple electrical issues by VERY CAREFULLY re-connecting both battery terminals. I don't like those connectors; its pretty easy to THINK you have them tight.