Malfunction / exchange of urgent questions!!!

Can someone tell me if a transmission may also be a
From 4.2 Q BJ 98 (i.e. to Facelift) into a
A8 Q BJ 97 without any problems??

Question hurries very, gladly also SMS answer on 0177 2730700

For example, on my engine cover is above the cylinders V8 and below 4.2
The V8 4.2 in a plaque below is to be slaughtered.
Also the one to be slaughtered has the "Chrome Bar in the Bumper"

It may be that he is a 5 valve and my 97 he is not; if yes
could one then nevertheless completely motor and transmission change???????

Since the matter is urgent and the local Audi partner seems to be questioned, I ask for a message as soon as possible.

PS: Must it be overhaupt a gear damage: My old A8 BJ 97 (see above) has been running on an emergency program since yesterday. The display "D 3 2 1 " or "5 4 3 2 " changes the color and it only takes place in the 4 or 5 gear of Automatic.

Maybe there's only oil missing. I pulled 10 heavy trailers two weeks ago, smelling like gear oil. Then two weeks without any problems and since yesterday shows this mistake. Do you need to change gears or what??? Who knows ???????????????????????????Question is very, very happy also SMS answer on 0177 2730700