Speedo cable ? Series 3.

I have just fitted a new cable inboard disc assembly. Very nice to. The speedo drive coupling that screws into my old hub is nylon and appears to be a different fitting to the new one. My lower inner speedo cable has a small brass bush fitted to the inner cable.
This will not slide into the new brass speedo drive. I have an ebay speedo with the thicker inner cable type fitting.
Am I missing something or have I got the inner cable the wrong way round.
This will not slide into the new brass speedo drive. I have an ebay speedo with the thicker inner cable type fitting.
Am I missing something or have I got the inner cable the wrong way round.