Engine number

Hi just wondering if any one can help my mk1 is fitted with a mk3 1.9 diesel engine does ant one know were the engine numbers are on these engines thanks  

We should put this as a sticky or into the technical section!

Its above spark plugs 3/4 on a flat portion of the block (just below the head) on a petrol engine big block, though I admit I don't know where it is on a diesel. Its normally necessary to sand or wire brush the rust away, so you can read the figures properly.