Could I interest you in a photo of the Holy Grail? Because that probably would be easier to find...
The closest thing I have ever seen is the photo on page 114 of Sturmgeschütz & it's variants, but the MG is not there and it doesn't appear to be much of the mount left either. About all it shows is the hole through the mantlet. It is comparable to this image of a late ausf G, an ex-Finnish vehicle;
You can see the hole, but nothing remains of the mount. The clamp would be similar to other coaxial mounts found in similar arrangements.