I have no personal experience with Diveney, but many cuemakers (including myself) use 3/8-16 weight bolts.
Just not clear about your post. Do you have a Diveney with a threaded hole in the butt but no bolt, or, no hole for a weight bolt and you want to add one?
I have a few around here so I got them out and took a picture for you .
In this picture they are setting on a bic pen so you can get a good idea
of the size compared to the pen .