I've generally re-used mufflers unless they were holed or otherwise damaged. I've purchased a couple new ones, they get pricey. That NAPA one is a different style compared to what that tractor originally had. The link you posted shows a muffler for the earlier Cub Cadets that don't have side panels. I actually used one like that on a build where I didn't put side panels on the tractor, so that style muffler worked out. Pictures here show how I used the heat shield (and fuel tank) from an earlier series--that made mounting the muffler easier. This was originally a 1450 but got a K301 transplant.
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