Any part can be replaced by a machinist. Or a new cylinder can be built entirely, or an existing new cylinder modified to fit. Since it's a bucket cylinder, they are usually the most abused on the machine, so I'd inspect the chrome before making any decision.
If this is the JD special wire lock ring style, then the thread only hold the gland tight to the ring, the ring does all the work, the threaded lock nut could easily be remade in a slightly smaller diameter and the gland threads cut clean at a smaller diameter. But I'm only guessing this is that style based on the age.