The Yoder Smokers Reinforced Pellet Cooker Burn Grate will fit in your YS480 and YS640 pellet smoker. This new burn grate is reinforced to limit any warping of steel that may happen during high heat cooks.
I upgraded when I couldn't bend my old burn grate back into position. The new design is way better. No more need to step on it and bend it back into shape after each cook. I have only used it a couple of times, but it appears to be a nice improvement.