I have made long arms for an 043 and an 044 by cutting the shafts of long shank spade bits . You can get both long rods from a 16” or 20” bit. With the longer bit, you probably still have a working bit left over.
They usually cost under $10 USD , so even if you have to buy a new bit it’s probably cheaper to just go to a hardware store and pick up a bit than to order rod from a steel supplier online. The steel is pretty good, but still cuts fine with a hacksaw and files.
Different size bits have different diameter shafts, so I advise you take your plane to the store for proper sizing. I can’t remember what size I used, but dim memory says something like a 3;4 or 7/8 bit.
I was fortunate to have used up bits to scrap, so they were free for me. We used a lot of long shank bits when I worked.
The drill bit actually sized better in the fence holes than the factory rods. The picture is of an 043 with home made rods. The bit is what i think fits an 044.
You will have to verify. Sometimes the rod diameters are different even for the same diameter bit.