Kittleson/Kettleson/Olson

Researching my husband's family history. His g-grandfather homesteaded in Antelope Montana named Christian Arthur Olson, His son, Carl Arthur Olson married Nettie Modahl in 1916 in Culbertson Montana. Carl had a brother named Otto. I've been told that "Olson" was originally "Kettleson/KIttleson"? They migrated to Minnesota and Nettie is buried I believe in Pelican Rapids? Searching for any history on either Kittleson or Modahl. Nettie came from Lars Modahl and Bertha Torkildson. Said she moved from Norway on a ship somewhere around 1909.