I came across a circuit using the 2N4992 where it seems to be used like a DIAC but it is much lower voltage than a 'normal' DIAC. I have attached a link to the (rather sparse) datasheet.
It has three terminals - anode I, gate, and anode II. How would I connect these terminals to get a DIAC like behaviour?
http://www.newark.com/pdfs/datashee...144.472586792.1594251888-790695252.1573597169

 

You would connect the SBS Anode 1 and Anode 2 terminals the way you would a DIAC, with the gate left open. EEGuide has a good writeup on the SBS.

 

Aha! It all becomes clear. Thanks @OBW0549