I did it!!

I used the FIND function!

Thank you for all your help!

Dim LastRow As Range 'to capture address of placement on tracker tab before it's copied to BU tab
Dim strCriteria As Long 'search address on audit #

strCriteria = wbSource.Sheets("Quality Review Input Sheet").Range("C5").Value

With wbDest.Sheets("QR Tracker Pivot Renewal")
Set LastRow = .Cells.Find(What:=strCriteria, _
After:=.Cells(1, 1), LookIn:=xlValues, _
LookAt:=xlWhole, SearchOrder:=xlByRows, _
SearchDirection:=xlNext, MatchCase:=False)
End With

'If LastRow Is Nothing Then MsgBox "No match"
If Not LastRow Is Nothing Then

    wsSource.Range("AP2").Value = LastRow.Row
    wsSource.Range("AQ2").Value = LastRow.Row + lBUCount

 End If