Pre facelift 4.2 A8 manual conversion
 

Hi everyone I own my first Audi since 8 months and I still love it. It's a 99 4.2 a8 (99 is prefacelift in america), the body and transmission both have 169k miles and the engine got rebuilt 34k miles ago. It runs really well and all but the tranny is acting weird sometimes ( jerky at low speed and plays between 4th and 5th all the time at around 40-60 mph). My question is; What are my options for a manual transmission swap..! I mean what parts I'm going to need, I see a lot of people doing it on a S8 but never an A8... I'm located in Canada so I know I must have to ship every part!

You will pretty much need all the same parts as the S8 conversion, plus the rear 4.11 diff.

You also might have an issue with the Flywheel. 40V cars have a more common flywheel bolt patter if I recall correctly. On the plus side, and it is a big plus, in Canada, you have access to the 01E 2.5 TDI gearbox with a .56 6th gear ratio which gives you a great low rev gear for highway cruising. Hard to find though. The alternative is to source the 6th input and output gears and swap them during a rebuild.

Some good info here: https://advancedautomotion.com/shop/

Here is another recent conversion: https://forums.quattroworld.com/a8/msgs/111543.phtml

I've seen people on ebay claiming a passat trans will work? or maybe it was the 4.2 a6? No idea but interested!