If anyone needs an OEM flexplate I have one from my '06 Sierra 5.3/4l60e removed at 50k miles when I did the 80e swap. Pay for shipping and its yours. Also have the passenger side 60e heat shield I'll throw in.

 

What flexplate did you use in its place?

 

My guess is the OEM with the spacer

 

I did a 4L80e swap, not sure of the part number but I got it from my local advance auto parts. I believe I told them a flexplate for a 2000-2006 truck with 6.0. It's been a few years but I think it was around $60-$70. My 4l80e came from a 2001 1500HD. No spacer required, simple swap. Circle D will make you a converter for a 60e bolt pattern and 80e spline, the 80e has 6 converter bolts and the 60e has 3 so I felt better swapping flex plates.