That's strange, I wonder why my PM's are not working... weird.
So you are putting the 98 Interior in a 96 Blazer, and a 98 LS1 in also?
Sounds like you are in for quite a mess.
I really am not sure what to tell you. The entire dash is controlled via class 2 serial data that will require both the ECM and BCM be present. You will need a proper program in the LS1 computer in order to make the dash work right, and you will also need a lot of the connections of the BCM in order for that to function properly. I don't know the details exactly, because I have never messed with what you are talking about, but I can guarantee it will be a huge headache.