will a 99 fbody ls1 computer and harness run my 04 ls6?

I'm trying to gather parts to make my ls6 short block whole again and need a harness and pcm. There is one for sale but it is a 98 fbody ls1 and I don't know if they are compatible. I will be tuning it when used.

 

The 98 LS1 pcm is different from the 99 and up. To answer your question about a 99 PCM is yes. It will work for an LS6.