Currently Running the below code, and need to make an edit to one part.

Sub VlookMultipleWorkbooks()

    Dim lookFor As Range
    Dim looktran As Range
    Dim shipdate As Long
    Dim srchRange As Range
    Dim srchtran As Range
    Dim lrow As Long
    Dim lcol As Long
    Dim dccol As Long
    Dim sccol As Long
    Dim transcol As Long
    Dim shipcol As Long
    Dim rowstart As Integer

    Dim book1 As Workbook
    Dim book2 As Workbook

    Dim book2Name As String
    book2Name = "DC_Data.xlsx"    'modify it as per your requirement

    Dim book2NamePath As String
    book2NamePath = "C:\Users\markf\OneDrive\" & book2Name

    Set book1 = ThisWorkbook
    
    If IsOpen(book2Name) = False Then Workbooks.Open (book2NamePath)
    Set book2 = Workbooks(book2Name)
    
    lcol = Cells(1, Columns.Count).End(xlToLeft).Column
        dccol = lcol + 1
        sccol = lcol + 2
        transcol = lcol + 3
        shipcol = lcol + 4
    
    lrow = Cells(Rows.Count, 1).End(xlUp).Row
    
        Cells(1, dccol).Value = "DC"
        Cells(1, sccol).Value = "SCAC"
        Cells(1, transcol).Value = "Transit Days"
        Cells(1, shipcol).Value = "Ship Date"
        

    rowstart = 2

    
    Do While rowstart <= lrow
    
        Set lookFor = book1.Sheets(1).Cells(rowstart, 3)
        Set srchRange = book2.Sheets(1).Range("A:B")
    
            Cells(rowstart, dccol).Value = Application.VLookup(lookFor, srchRange, 2, False)
        
        
        
        Set looktran = book1.Sheets(1).Cells(rowstart, dccol)
        Set srchtran = book2.Sheets(2).Range("A:C")
        
            Cells(rowstart, sccol).Value = Application.VLookup(looktran, srchtran, 2, False)
            Cells(rowstart, transcol).Value = Application.VLookup(looktran, srchtran, 3, False)
            
            Cells(rowstart, shipcol).Formula = "=Workday(K" & rowstart & ",-2-" & Cells(rowstart, transcol).Value & ")"
    
            rowstart = rowstart + 1

    Loop

    
    

End Sub


Column K as referenced in the below formula may really not always be column K.

What I am looking to do is replace that with a variable that would be assigned a column based on specific text (say Stock) that would be in the header row of the data.
Cells(rowstart, shipcol).Formula = "=Workday(K" & rowstart & ",-2-" & Cells(rowstart, transcol).Value & ")"
How do I go about doing something like this?