Thanks so from the sounds of it
"Don't quote me, but I think I remember where it is. I would go to the gearbox end of the block, and look just above the bellhousing (just under the head) on the front bank. I guess there will be a few things in the way, including water pipes and possibly the front turbo cold air inlet pipe. But like I said, please don't hold me to it!"
I will have a look later to see if I can find it as I got a blue slip but it has a comment that they could not find the engine number and it needs to be checked.
Dont stress Emanuel, I got the same thing when I had my road worthy done. The easiest thing to do is to remove the air intake and shine a torch down on the block then spray a shit load of WD40 down there so that the surface becomes reflective. One thing to watch is that the number is split across two lines. One above the other, sorta like this: