Actually, all Allis-chalmers lawn and garden tractors were built by Simplicity, and for every AC lawn and garden model there ever was, there was also a simplicity twin. Because AC wholly owned Simplicity.
B&S actually bought simplicity, and simplicity is still kinda its own company, with its own dealer network. B&S PPG (Power Products Group) also owns snapper and I think husquavarna......
But, sorry to say, AC is gone. If they re-appear, it'll be like Massey-furgeson, just a shadow of its former self......