Huge data index/match replacement

You are welcome.
Of course the macro on post #3 won't work for your newest file on post #4, they have different layout.
This is the macro for your newest file on post #4 :

Sub Test()
  Dim rng As Range, arrDec, arrCon, arrTop, arrLeft, i As Long, j As Long, p1 As Long, p2 As Long, startTime As Single, endTime As Single

  'Log start timer
  startTime = Timer

  'Get arrays
  arrDec = Sheets("decimal").Range("A1").CurrentRegion.Value
  With Sheets("Cty Contracts").Range("A1").CurrentRegion
    Set rng = .Range("E2:" & Split(.Address, ":")(1))
    arrCon = Sheets("Contract").Range(rng.Address).Value
    arrTop = rng.Offset(-1).Resize(1).Value
    arrLeft = rng.Offset(, -rng.Column + 1).Resize(, 1).Value
  End With

  'Change items to be matched to uppercase
  For i = 1 To UBound(arrDec, 1): arrDec(i, 1) = UCase$(arrDec(i, 1)): Next i
  For i = 1 To UBound(arrDec, 2): arrDec(1, i) = UCase$(arrDec(1, i)): Next i
  For i = 1 To UBound(arrTop, 2): arrTop(1, i) = UCase$(arrTop(1, i)): Next i
  For i = 1 To UBound(arrLeft, 1): arrLeft(i, 1) = UCase$(arrLeft(i, 1)): Next i

  'Get index
  For i = 1 To UBound(arrTop, 2)
      For j = 1 To UBound(arrDec, 2)
          If arrTop(1, i) = arrDec(1, j) Or Left$(arrTop(1, i), 12) = arrDec(1, j) Then arrTop(1, i) = j: Exit For
      Next j
      If Not IsNumeric(arrTop(1, i)) Then arrTop(1, i) = 0
  Next i
  For i = 1 To UBound(arrLeft, 1)
      For j = 1 To UBound(arrDec, 1)
          If arrLeft(i, 1) = arrDec(j, 1) Then arrLeft(i, 1) = j: Exit For
      Next j
      If Not IsNumeric(arrLeft(i, 1)) Then arrLeft(i, 1) = 0
  Next i

  'Calc
  For i = 1 To UBound(arrCon, 1)
      p1 = arrLeft(i, 1)
      If p1 > 0 Then
         For j = 1 To UBound(arrCon, 2)
             p2 = arrTop(1, j)
             If p2 > 0 Then
                arrCon(i, j) = arrCon(i, j) / arrDec(p1, p2)
             End If
         Next j
      End If
  Next i

  'Write output
  Application.ScreenUpdating = False
    rng.Resize(UBound(arrCon, 1), UBound(arrCon, 2)).Value = arrCon
  Application.ScreenUpdating = True
  
  'Log end timer
  endTime = Timer
  Debug.Print (endTime - startTime) & " seconds have passed [VBA]"
End Sub