I Emailed Chevron and asked the question if they made the Hy-Gard Fluids for them, and they Replied with the following.
Our Chevron (All Weather THF Full Synthetic) is "John Deere Hy-Gard J20D", Our Chevron (THF-1000) is "John Deere Hy-Gard J20C".
They would not give into any further details...