Check out this thread. It looks like he found a way to custom make a cable.
https://www.orangetractortalks.com/forums/threads/l4200-gst-cable-broke.47152/#post-451379
I know this is an old post, but a member on the TractorbyNet Forum has a GST Cable problem. He could benefit from your experience. Here is the thread
https://www.tractorbynet.com/forums/threads/l3010-gst-will-not-shift-out-of-neutral.435422/