There should be a elbow fitting that screws into the threaded hole. My early 97 E320 ( built June 96 ) uses such a fitting.

My 97 SL320 ( same engine as the E320 ) does not use such a fitting , the bleed hose runs into the rad.

The elbow fitting might be in the parts kit just not shown in the pic, no way to tell unless someone looks in the package.

By the way, the E320 is being broken for parts. The motor, trans and some other odd bits are being used for other projects but, other parts are for sale.