Decoding the 263 production numbers

[TABLE]

<tbody>[TR]

[TD=bgcolor: #C0C0C0]1951[/TD]

[TD]40(std)[/TD]

[TD]6240128-4[/TD]

[TD=bgcolor: #C0C0C0]1952[/TD]

[TD]40(std)[/TD]

[TD]6646232-4[/TD]

[TD=bgcolor: #C0C0C0] [/TD]

[TD] [/TD]

[TD] [/TD]

[/TR]

[TR]

[TD]40(dyn)[/TD]

[TD]6240100-4[/TD]

[TD]40(dyn)[/TD]

[TD]6646230-4[/TD]

[TD] [/TD]

[TD] [/TD]

[/TR]

[TR]

[TD]50(std)[/TD]

[TD]6240564-5[/TD]

[TD]50(std)[/TD]

[TD]6647024-5[/TD]

[TD] [/TD]

[TD] [/TD]

[/TR]

[TR]

[TD]50(dyn)[/TD]

[TD]6240100-5[/TD]

[TD]50(dyn)[/TD]

[TD]6646230-5[/TD]

[TD] [/TD]

[TD] [/TD]

[/TR]

[TR]

[TD]70[/TD]

[TD]6240161-7[/TD]

[TD]70[/TD]

[TD]6652000-7[/TD]

[/TR]

</tbody>[/TABLE]

Looking at this chart, one could say a 51 year correct 263 in a 50 series/dynaflow serial would be between 624xxxx-5 and 664xxxx-5?

Yes, as long as the engine number ends in a 5 it is correct. There is no such thing as "numbers matching" for 1956 and earlier. Also, the engine numbers didn't have a dash (-) between the sequential portion of the number and the series digit, just more or less space depending on who was doing the stamping. The dash is shown in literature only.