Transmission thump/shunt

[David's8]

ZF online catalogue has 3 gearboxes (all 5HP 24A):

1. Part No. ZF 1058 020 013 Engine Code : BCS, AQH
Transmission ID : ECY (1058 020 013)
S8 Quattro 265kW 99-02, Audi 01L 300 041S

2. Part No. ZF 1058 020 022 Engine Code : AYS, AVP
Transmission ID : FBG (1058 020 022)
4.2 Quattro 228kW 98-02
S8 Quattro 265kW 99-02
[No Audi code given]

3. Part No. ZF 1058 020 030 Engine Code : AYS, AVP
Transmission ID : FBG (1058 020 030)
4.2 Quattro 228kW 98-02
S8 Quattro 265kW 99-02
Audi 01L 300 042P

Not sure what the difference is between 2 and 3 which have the same engine codes and models but have adifferent ZF part No.