Ati Radeon Hd 5770 Graphics For Mac

I have a 2008 Mac Pro, running OSX 10.8.5. Just installed AMD Radeon 5770 graphics card (Apple says this isn't supported; users I read said it works despite what Apple says in knowledge article (http://support.apple.com/kb/TS3477). When I restarted, the system said my card was a Radeon HD 5000, not 5770. AMD's web site not clear about driver upgrade (and I believe I have to do this, since I took out the old graphics card (ATI Radeon HD 2600 that came with the Mac Pro at purchase). Didn't get a clear answer, yet, from Apple support. Anyone experience this? Does anyone know which driver to manually download from AMD's site? It's not clear, and they also suggested, talk to Apple to get driver support. Here's where I went, and found the choice not clearly mapped out for the Mac (and their autodetect software works only for XP:

Ati Radeon Hd 5770 1gb
Ati Radeon 5770 Software
Apple Ati Radeon Hd 5770 Graphics Upgrade Kit For Mac Pro

The Radeon HD 5770 Mac Edition was a graphics card by ATI, launched in July 2010. Built on the 40 nm process, and based on the Juniper graphics processor, in its Juniper XT variant, the card supports DirectX 11.2. The Juniper graphics processor is an average sized chip with a die area of 166 mm² and 1,040 million transistors.
(.) Apple MC742ZM/A OEM/ATI Radeon HD 5770 Graphics Card for Mac Pro. 1GB of GDDR5 memory, PCI Express 2.0, two Mini DisplayPort outputs, and one dual-link DVI port. Up to 2560 x 1600 resolution. Used, Tested-Good, Video Card Only. 90 Day OWC Fulfilled Warranty.
For impressive graphics processing power, the ATI Radeon HD 5770 with 1GB of GDDR5 memory is a great choice for visual creative, scientific, and technical applications. ATI Radeon HD 5770 includes three video ports: two Mini DisplayPorts and one dual-link DVI port.

I'm looking for ATI Radeon HD 5770 Drivers For MAC. All I can find are drivers for the PC versions.