The original Smiths Industries angle drive part number is BG2401/11
The Speedograph replacement would be a variant of the RGB2401:
http://www.speedograph-richfield.com/html/rgb2401.html
However, Speedograph will no longer manufacture the DeLorean variant of this drive. I have tried and failed at getting them to produce a batch, they cited 'health and safety' as their reasons for being unable to manufacture it.
I was told that someone had complained that the supplied nut had cracked on their unit, so I believe Speedograph are now doing a CYA with the 'health and safety' claim so that they don't get a potential lawsuit come their way.
For clarity, the Speedograph unit was previously supplied complete with the nut already in place as per the example pictures shown below.
When I was speaking with them on this however, I specifically advised them the nut was NOT required for our application as we can simply swap the nut from our old angle drive.
Attachment 53142 Attachment 53141
As others have mentioned here they were built like a tank, I've had one on my car for 6 years and 20k+ miles and it's still going strong.