It's definitely not a 3/4 pipe thread. I check that out last night.
I've been through this situation myself and engaged the help of Barry Weeks at the time. Between the two of us - mostly him, we found no dies available that are that thread size and you can totally forget the the left hand thread. You probably could find a LH thread at an old shop somewhere or a fully equipped shop. It's such an odd thing, they are difficult to find. Finally, we cut off the RH thread end and re-threaded it with a 3/4-16 die. It worked fine.
About the only other thing you can do is cut the tie rod somewhere in the non-threaded area, remove the a portion and weld it back together to the length you need.
I think we all would be interested to hear if you do come up with the dies you need and/or what you end up doing!
