Extraction/conversion of PAK files

I know someone probably posted this a while back, but does anyone know of any tools to extract and convert PAK files, like the ones from the Uncharted games? I’d like to retrieve some models from the Uncharted games, like the characters and vehicles. The characters would be nice, and the vehicles could be useful. They’re of really good quality, and it seems that Uncharted 3 has the most accurate Rolls Royce in gaming history. We also need to replace the ugly and broken GMOW Defender 90. So, anyone know of any tools we could use?