This is why going to a meeting was not only fun but informative! I have vintage 26 grills. As many of you know, the grates on these sit lower than the modern 26. I like to use my slow n sear with the 26, but it barely fits, and the grates sit basically on top of the sns. At the Chicago meetup, there was member's Aristocrat with the modern grate. It will fit essentially nestled on the walls of the inside of your kettle above the grate strap tabs. You have to level it out by eye, but once it has some weight on it, it won't move. You gain some extra height above the charcoal grate to fit the slow and sear, which I like for protecting porcelain. You also have a little extra space and the benefit of slip up sides. Learn something new everyday!
BTW: Slow n Sear's 26 304 SS grate is $89.99 vs. Weber, which is $109.99 and also stainless.