i just did a 6l80e swap and put a CircleD flexplate before i put it in... i have the noise damm similar to this...it comes n goes now though at first start up then on and offf.. tech at dealer says it was my starter sticking and un sticking on n off..seeing this thread im thinking on spacers and see if it goes away..

 

Which starter shims for NNBS ? ...ive looked at Summit and it stops at 2002 ... Are those the same for 08?

 

I used steel washers