New engine dodgey engine number????

[muso]

I had this Ecotec V6 engine (yes I know it's a Ford forum ) installed in my car (won't say where) the engine is fine and runs well and is supposed to be (according to the paper work) from a VY with low km's and side damage.
But when I had a look at the engine number it appears to be either unreadable or removed! I couldn't view the actual engine before they installed it because it was at a storage warehouse but was given a receipt quoting the engine number. The receipt shows a late model VY engine number but on the block appears nothing........dodgey or just dirty and needs a clean.
The number on my old engine is deeply stamped into the engine block in a dot matrix form (see photo)
It has a warranty period, should I query it? Is there a way of cleaning it so I can see for sure? I've already tried wet rub paper but it doesn't do much, the fresh scratches were done by me trying to clean it with a screw driver initially.
The engine runs just fine but without being able to read the number on the engine block I can't tell if it's from a VY or VT or even VS.
Has this engine's block number been deliberately removed?

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