ZZP's prices (for now) are pretty good for the #6 tranny fluid.
ZZP is basically selling it for $4.99/qt. ($19.99/gal) where as the current dealer price currently is $8.66/qt. retail. The dealerships I talked to cannot buy it in bulk currently, so once they do or can, the price could go down some for them, and even more for me when I "walk in and go shopping" like I do for my other parts and supplies.
From what I have been told, GM has been using a synthetic blend oils and lubes in many of their models since 2006. Not all the cars and trucks from 2006 on are using a synthetic blend in everything, many of them can have the old regular stuff, if you will, in there too depending on model.
Just my findings and knowledge that I know of being passed on.
~F~