If you look around my website, you can see I have a number of different toroidal AC power transformers, many WITHOUT the mounting kits.
After sorting through my boxes and boxes of left over production spare parts, I have found some mounting kits (at last)

These mounting kits are all ex Australian audio equipment manufacturing, there is nothing wrong with them at all, they have just been sitting in packets waiting for their “purpose in life” don’t we all?

This is one of the mounting kits …

SAFETY CAUTION: When mounting toroidal transformers think carefully about what you are doing! Remember that it is important that your transformer be mounted in such a way that the mounting screw and the metal chassis will not form a closed loop through the center and thereby create a shorted turn on the transformer Believe me, this is NOT a good thing to do!

TOROIDAL TRANSFORMER MOUNTING KIT (3 pieces)
The kit comprises:
Rubber (not plastic) base disc
Steel top disc with indent in the centre
Bolt with nut
DIMENSIONS:135mm diameter top and bottom discs
Hex head bolt is 71mm length
NOTE: If the bolt length does not suit your application, these are easy to find at your local hardware store – no special requirements.

COSMETIC CONDITION:
NEW Old Stock
Sealed in a clear plastic packet