Actually, you can use the UPD for the LJ4200, 4250, 4050, etc. The UPD works for a wide variety of models. The below link is to HP's information site on the UPD. The Specifications tab shows a comprehensive list of the printers that can use the UPD.
http://h20338.www2.hp.com/hpsub/cache/343033-0-0-225-121.html?jumpid=ex_r2845_go/updmichko