Need Rubber Instrument Cups

I have a 1978 Bonneville that needs new rubber cups that hold the speedo and tach. Are there different suppliers? The reproductions that are on the bike are awful.......too big and too soft. I would like to find a better grade of cups if possible. Any help to steer me in the right direction would be appreciated.

 

Thanks Mr.B. I would like to find a supplier in the states.

 

Thanks for the info Jim