I don’t know if Tormach’s UK dealer does tooling or just machines but worth a try and they will be genuine parts not copies that you tend to find on ebay.  Or order from the US.

If push comes to shove, why not get an ER32 taper shank holder and make up a holder with an internal MT taper to suit the collet holder. The parallel shank holder can have provision for a drawbar to retain the taper shank.

HTH

Howard

If Modifying other ER chucks you would have to add the collar to get the height registration that the TTS holders incorporate and if it is to go into a ATC equipped machine then you also need the groove to allow it to be held, this is a featrue missing from a lot of the copies too.

You could not run a longer shank if using ATC so the grip of an MT would be much reduced and they say you have to watch the load on a ER32 anyway as it can pull out of the spindle collet if loaded too much.