Need a complete rear differential assembly (3T51 299HUQ0113378G080111E) for a 2008 Audi A4 S-line Quattro with a 2.0L turbo and six-speed manual transmission. Do all B7 series Audi's utilize the same differential? Is the 3.89 final drive ratio the same in all B7 series or are automatics and manual transmission vehicle different? Do you have somewhere were I can source this unit? What is the difference between the HUQ, HUP, HNP, and HNL differentials? Thanks!