@29tx Killa Grilla is the only one I recall that currently makes one that fits the vintage 26" Webers. They are SS and the least expensive version is $120, but everyone that has them say they use the thickest bar stock and make a great product.
I don't remember the brand, but there was a brand that made a chrome plated steel slightly smaller grate a number of years ago that fit the vintage Weber 26. Some people bought a bunch when they were eventually clearanced out. If you can't find a thread on it, I'll look it up. I ran across one listed locally for a reasonable price last year, but didn't buy it.
Something to be aware of. The vintage ones take a slightly smaller diameter grate. The reason for this is that the grate tabs sat lower in the bowl (thus in an area with a slightly smaller diameter) than the current bowls where the tabs were raised so the grates are further from the coals. I bought a Chief a number of years ago & the guy had a vintage grate, but made a ring out of expanded steel mesh that he placed on the tabs to hold the old grate higher up away from the coals because he mostly used it for smoking.
Eventually, I stumbled across someone who listed (somewhat locally) a new Weber grate from a new 26. He did not list it as SS and did not appear to be aware it was SS and only asked $25. So, I arranged to buy it when I was picking something else up in that direction. I use it on top of that expanded metal ring that I have sitting on the tabs. Just thought I'd mention it because, depending on what you will use it for, you could go with a standard size and save a couple bucks. If you are willing to pony up for a Killa Grilla grate, you could still raise it for smoking and set it lower for some better grill sear marks on steaks, etc when it is closer to the coals. (Damn, I'm almost convincing myself and I really don't want to spend $120 on a grate).