which Engine Cover for 2.7 TDI?

[localknoxville]

I'm on the lookout for an engine cover for my 2008 A6 Avant Le Mans 2.7 TDI
Found a few on flebay but they all look the same and have the same number: 059 103 925 but all have different letters on the end, some are AG, BB or AG
Does it matter which one? as they all look exactly the same as far as I can see

 

[B5NUT]

Just minor revision changes over the years but they all will fit.