Hi Colin, on a 2006 D5 it will be a Euro4 with DPF.
Two versions were made 163 ( not to be confused with the Euro 3 163 ) and the 185.
The Geartronic gearbox will be a 6 speed and geartronic alows you to move the gearlever over to the left and select gears manually.
The 6 speed box is a better ( stronger ) box than the earlier 5 speed geartronic BUT make sure that you get it thoroughly warmed through and check for hard changes, slipping, flaring prior to purchase
If all is well and you buy it, change the gearbox fluid straight away and use JWS 3309 spec oil. This can ensure that a healthy box stays that way for many many miles.
If you do plenty of decent length journies, the DPF should look after itself.
Lastly, if possible stick a good code reader on it prior to purchase to see what it throws up ( remembering that some could be old stored codes and no longer relevant.
