I've been emailing Dbit since January requesting them. I'm just not getting a response. I've just chalked it up to pandemic and supply chain problems that just about everyone is having. I have a pair old full-height Shugart SA-851's that I'd like to use to write disks with that would need the exterrnal TG43 signal. They seem to read disks fine. I'm currently writing with a Tandon 848-02 Model II that does have a jumper for internal handling of the TG42. I really just want to have a couple of these on hand just in case.
very few drives actually have a TG43 signal, look at the manuals on bitsavers.
Take a look here - https://www.ebay.com/itm/114924378003?var=415057297439 . They are being produced by CuriousMarc's friend Antoine.