If it's your engine serial number you need for your X7 John, then it's:
10 DYWT 4009151
"A" Vehicle’s VIN no. (The number is engraved on the body on the upper part of the wheelarch).
"B" After Sales / Replacement Parts identification label - Tyre information and pressures (Label on the front pillar on the driver’s door side).
"C" Vehicle manufacturer’s label (Label affixed to the base of the centre pillar) - On the right-hand side .
"D" Repeat of the vehicle VIN (Visible through the windscreen).
"E" Gearbox reference - production serial number.
"F" Engine legislative type - production serial number.