When I built a stand (old Screaming Eagle design) I used aircraft cables from the local hardware store and twisted them a lot on the ends. I then used multiple cable clamps to hold the ends. Worked great.
My local True Value Hardware will custom swage aircraft cables. If I couldn’t get replacements from the manufacture I’d head to the hardware and see what they could do for you.
They out of business????
Found this from 2011: I have a hunters view treestand, found out they are out of business, looking for a source for replacement parts, particularly the 2 cables used to hold the stand to the tree.
I ordered some from Gorilla this winter. They we 29.5″ hole to hole (centers). I think it cost me about $15 shipped. If that is the length you need, try them. They may have different lengths for different models. I would measure the length and hole diameter(s) and start calling stand makers.