Hi ajohnson640. Welcome to the forum. This is something that should be asked of an Audi mechanic right at the dealership. If this were an all-wheel-drive Caravan, all you'd have to do is remove the rear driveshaft and viscous coupling. It's a twenty minute job, but that still leaves the rear differential spinning as you drive. The entire rear axle can be replaced with the parts from the regular front-wheel-drive model. That just leaves the 3" long output shaft from the front differential spinning.
Audi and Volkswagen tend to do things quite differently than any other manufacturer so I don't want to say this is as simple as on a Chrysler product, but one clue is if your model was available in a front-wheel-drive version. If it was not, there may be something in the design of the drivetrain that requires the rear portion to be there. That's where the dealership mechanics are your best resource. You must also look at the reason you want to make this modification. If you have a leaking seal or a noisy bearing, you have to remove enough stuff to include those parts. You can't let rotating parts remain on the vehicle if they will no longer be supported and could whip around and get out-of-balance.