What's needed to bolt a 6.0 to a 4l60-E?? Isn't there some kind of spacer of some sort needed??

 

If the engine is 01+ all you need to do is swap your flexplate over from the 5.3

Or, if it was already bolted to a 60E then you don't need to change anything.

 

so just bolt my 5.3 flexplate up and go??

 

Yep, the spacer is generally needed when you are putting an 80E behind something that had a 60e from the factory. I had to use one when I bolted my 80E up to the LQ9. The two trannies use different flexplates. As long as your motor is 01+ it should have the same length crank as your 5.3, so you should be able to bolt up the flexplate and go.