Sears made three Sportster models in 72. There was a 244, a 335 and a 450W. The 244 had a Polaris EC25P engine, the 335 came with a Polaris EC34P engine and the 450W came with a Polaris EC40P. You're correct about the sleds being made by Polaris. I think they were either Mustang or Charger sleds with the Sears name on them so parts should be fairly easy to find parts.
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