Stumbled upon this while researching a C6 purchase. Seems to be some specific changes for the CTS-V.
http://media.gm.com/us/powertrain/en/product_services/whats%20new/06%20man%20trans/06%20_PWT_Tremec%20T56%20(MM6).pdf
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http://media.gm.com/us/powertrain/en/product_services/whats%20new/06%20man%20trans/06%20_PWT_Tremec%20T56%20(MM6).pdf
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