The number 20 is stamped on my Dec 1950 engine case

[50Splitman]

There is the number "20", a "&" symbol, and three other 4 digit numbers are stamped on the front of my engine case below the engine number. Does anyone know what these numbers mean?

I also have a July 1950 engine and it doesn't have any of these things stamped in this location.

[KTPhil]

Could represent machining of the crank saddles, or planing of the case. VW did both when rebuilding.
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Current Fleet:
- '71 Fastback
- '69 Westfalia
Retired:
- '67 Beetle
- '65 Beetle (x2)
- '65 Bus
- '71 Squareback

[Zwitterkafer]

Planed cases should additionally have the letter P stamped in that area.
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"Criticism comes easier than Craftsmanship"
- Zeuxius, 400 BC

[wagen19]