Hallo Keith,
I use on my SD 300 / MD 65 a system similar to the folowing
**LINK**
you have to downlod the "Katalog" with download and on page 34 there is Elmars System. My system is similar ,but I do not know where I have bought it. As I remember it was a competitor of him ,but he is out of service.
Proxxon the former dealer in west germany of the hobbymat have a smaller system .
Please look at this **LINK**
Please look to the middle of these page **LINK**
there are universal tool posts.
I have my SD 300 converted to a 3 phase motor with inverter. This was a big step forward in useage. With the fastes gear with 1400 rpm motor and the inverter you can cut threads from M3 without breaking the thread drill.
The lucky sad story was the single phase motor shut down after 35 years of service and that forced me to use rge 3 phase setup.
I hope that help.
Werner