Help with auto Fill

[jln via OfficeKB.com]

OK here is what I trying to do. I need to count the number of used rows in
column A and place "N" in column AU when there is anything in column A of
that row. Im have a major brain Fart here.

Dim SourceRange As Excel.Range
Dim fillRange As Excel.Range
Dim rng4 As Excel.Range

With Worksheets("shtXL")
Set rng4 = .Cells(.Rows.Count, 1).End(xlUp)
If rng4.Row < 1 Then
Exit Sub
Else
Set SourceRange = .Range("AU8")
SourceRange.Value = "N"
Set fillRange = .Range(SourceRange, .Cells(rng4.Row, "AU"))
SourceRange.AutoFill Destination:=fillRange, Type:=xlFillValues
End If
End With