Here is another shot.

Sorry. Nothing will make that wound better.

It won't save it for the long term, but I have a previous neighbor that tried something and it's still working four years down the road--

His crimson queen split like that, and he pushed the two pieces back together, drilled a very small hole through the two pieces, and put a bolt through the hole with a small nut on the other side. He slowly tightened it, then left it in place for good.

This tree isn't very important to him-- it's just a part of his landscaping-- and he didn't mind experimenting a little. I was surprised it worked. My guess is that eventually the plant will succumb, but it's worked for years now and both branches are still going strong.

Has anyone else used a technique like this?

That wound is much too old to try and join it together. A fresh wound would have been tough enough given the weight on either side, but as Jean already said, "Nothing will make that wound better".

tj

You would probably want to support it so as not to allow the trunk to split anymore. The wound seems to be healed over and the damage should not be a significant threat to the health of the tree. Both sides are still transferring water and nutrients thru their respective cambium layers. Damaged was probably caused this cold winter. snow and ice!! The bolt trick will absolutely work for support. And the above mentioned bolted tree will not succumb from that procedure. The trunk is not grafted back together but the nut and bolt just prevents further injury to the same wound.
You just need to make sure it won't split more at the same spot, even if you just do something as easy as tying the 2 pieces together temporary until a bolt or something similar can be done.