Mike, the W on the toolholder's indicates they are original Myford Dickson manufacture, some of the clones fit fairly well but none are as good as the originals. The best you will get are Bison form Rotagrip the S00 size is the correct one but they are pricy ! Most of the regular suppliers offer clones and at much lower prices.
Regards John
PS there was a firm called A & R Precision making them in the UK excellent quality but they disappeared– however I would recommend you go to the forum search and just put in Dickson lots of info comes up
Edited By JohnF on 18/02/2019 22:57:03