....how do I identify the heads I have?

[yeti]

I am a little new at this, but, I am rebuilding a 6.5 for my 82 and I need to know if the heads I got from the scrap yard are 6.2 or 6.5. If they are 6.5 heads I will get them checked. Don't want to spend the money if they are 6.2s. How can I tell the difference and is there a difference between the turbo and non-turbo heads?

[More Power]

What are the casting numbers? There should be a seven digit casting number under the valve covers. :)

Jim