I modelled a simple holder for the Subaru DST-i diagnostic interface which I mounted to the side of one of my tool cabinets. It has 2 mounting holes which are 25mm between hole centres, and are 6mm in diameter.

I'm not sure how many different variants of DST-i units are available globally, but it suits the 2 models used here in Australia as shown in the photo (One type with the colour screen, and the other type with no screen). The inside measurements are 36x138mm, and the outside height is 75mm.