We used heaps of -GU256x64-332, GU256x64-372, GU256x64-355, GU256x64-900, GU256x64-3900 on a LXE 900MHz radio terminal -The MDT1280.
I would buy dead units from USA for ~$100-200 and rip the VFDs out of them. I do recall the GU256x64-315, but I'd have to get to my shipping
container to see if there's anything left. You can check out LXE1280, 1290, 2280, 2285 to find out if any models used that exact part.
I have the pdfs for the models I quoted above, but would have to do a search through archives for the -315.
They were used a lot in radio terminals, hopefully, that may help. If you get stuck, I can do the big search :-)
Actually, at one point, I did make an interface so that I could run all the new LCDs, but again, long time ago. The code wasn't that hard to reverse.