Just for information. I had my A4LD rebuilt locally for about $1700 (taxes included) ~18 months ago.
That's with them doing all of the work, one part took a couple of weeks to source. I could not find it myself so that alone meant i wasn't doing it.
You have to either flush or replace the converter and cooler and lines. Easy for a shop, less so at home.
There are upgrades that can be done on the BII transmissions that were put in place in later years, this shop did those.
No it wasn't cheap, but it wasn't a rip-off either.