Somebody at Winnebago is making up new stories if they say Itasca was "bought." Winnebago created Itasca to put a motorhome on a Chevrolet chassis at a time when there was a contractual obligation to build the Winnebago motor home on chassis from Chrysler Corp.
That became moot when Chrysler left the medium truck and chassis business, terms of the first Federal bailout. Winnebago as a corporation has used both brand names in different ways since.
Late 1990s through middle of first decade this century, Itasca models were marketed as equivalent to Winnebago models. In C's, Spirit was equivalent to the entry level Minnie, Sundancer was equivalent to upscale MinnieWinnie. The Winnebago got a Chalet brand marketed for the rental market, for which there was not Itasca equivalent. So in that sense, one might say Itasca was a step up, from the Chalet at least.