Believe the OP's latest post did say:
.. the value from 'ED Numbers'!B1,
and the value from 'ED Numbers'!C1

(I fell for the line "8" which s/he posted yesterday)

in which case, perhaps a slight tweak to your formula in B1

Try this in B1:
="HD_SN "&'ED Numbers'!$A$23&INDEX('ED Numbers'!$B:$B,
(ROW(1:1)-1)/3+1)&INDEX('ED Numbers'!$C:$C,(ROW(1:1)-1)/3+1)&"T"
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Rgds
Max
xl 97
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Singapore, GMT+8
xdemechanik
http://savefile.com/projects/236895
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