Sears, Wards, etc carried various models of bikes and karts throughout the sixties and seventies that were badged with their logos, or logos of the originating MFGR, etc. Marketing.
So with an original tag on original paint, your machine is telling us the real story. When I was searching around, I saw some photos under the "U-ship" site of the belts and linkages. I think they might have been offered with various power plants as well.