I have asked a few pages on FB and it seems everyone claims to be a pro and know for sure BUT the answers are usually split. Half the people say I have to use a spacer and half said no.

2012 Gen 4 engine (5.3L) and using a 2004 model 4L80E transmission. I have a flat GM flexplate that I ordered (No it did not come with the spacer as pictured)

 

The little spacer that's like 6" in diameter, right? Yes, you need that.

Is this like a super high performance build? If you aren't pushing huge numbers, you can use the ATP brand from like advanced auto parts. Use a GMT 800 suburban 2500 LQ4 for the vehicle. It's a standard replacement flex plate and comes with the little spacer. Just get the longer bolts x6.

That flex plate is even cheaper on Amazon if you really want to save more money.