Gear Compatibility: A Comprehensive Guide

Warm greetings!

I own an A6 Avant with an AJM engine and a 5-speed transmission.

Which 6-speed transmission can I install retroactively?

Of course, I started by using the search function, and I came across the following:
Transmission assignment A6 AJM: DUK (gearbox).
Gearbox options for Passat models with AJM and ATJ engines: DUK, EHW, ELN, etc.

Can I now assume, for example, that I can install, say, an ELN transmission in my A6?

DUK and ELN differ in: 1. The diameter of the clutch disc, and 2. The dual-mass flywheel.

Thank you very much for any response.

Franz.