Good luck finding new one, it has not been stocked by Audi since 2001. For the used one it's probably best to look for somebody breaking old S8 on e-bay and asking them if they have the right badge for sale.

Also would like to mention that 2ZZ is not what determines old/new part, its just a colour code for chrome which applies to both new and old style. The difference is in A, old style is 4D0853735 without A.

What about something very similar if you can't source the S8 one, and a little bit of work with a dremmel (or local jeweller). There are the old style S6 emblems available on eBay for 39 euro:

https://www.ebay.de/itm/4A5853736C-N...6/311329390729

Plain one here with no model badging:
It's in North Carolina, so you'll have to enquire about freight

https://m.ebay.co.uk/itm/Audi-Sport-...-/202262512726

I know somebody who has just bought a Pre Facelift 4.2 A8 which has an original S8 Badge on the rear of it and is likely to remove it and sell it if you are interested, looks to be in good condition but if you PM me your details then I will get him to contact you direct when he's removed the badge +++

Was it a 4 speed in the end?

Unfortunately not it's a five speed but at 70k on the clock.might be worth putting it on a gearbox oil change programme going forwards