I may have one I can measure kicking about. It's slightly deformed so might not be 100% accurate but something to go on.
The one pictured looks pretty solid, you'd need the internal diameter too to drill out. Not an easy task (I've done it myself for the same reason), and hot elastomer really burns if it gets on your skin.
Looking at the pic, using the laptop as some sort of perspective, the rod you have looks to be a little narrow.