Genesis 11:13

And after he had become the father of Shelah, Arphaxad lived 403 years and had other sons and daughters.

Note Hebrew; LXX (see also Luke 3:35–36) 12 When Arphaxad was 135 years old, he became the father of Cainan. 13 And after he had become the father of Cainan, Arphaxad lived 430 years and had other sons and daughters, and then he died. When Cainan had lived 130 years, he became the father of Shelah. And after he had become the father of Shelah, Cainan lived 330 years and had other sons and daughters. Note that LXX also adds 100 years to the ages of Shelah, Eber, Peleg, Reu, Serug, and Nahor in this genealogy.

And Arphaxad lived after he begat Salah four hundred and three years, and begat sons and daughters.

Arpachshad lived four hundred three years after he became the father of Shelah, and became the father of more sons and daughters.

and Arpachshad lived after he begat Shelah four hundred and three years, and begat sons and daughters.