Those rods are 3/8" in diameter. If you're just after function, a pair of 3/8" bolts from your hardware store, with the threaded part and the head cut off, will do the job. A little filing on the cut ends will smooth off the swarf from the cut.
Bolts like that commonly come in Grade 5 and Grade 8. I'd lean toward Grade 8 bolts, because they'll likely be smoother and certainly stiffer, with a harder surface (less likely to get divots from the clamping screws). But look at them in the store and decide. Cutting off the parts you don't need on two Grade 8 bolts may wear out a hacksaw blade, but that's not a big cost.