Greetings,
I have a DAO P239 in .40. I want tgo convert it to a DA/SA.
From what I've seen, I need a new hammer, the decock lever and spring and the bearing piece the lever pivots on.
Is it that easy?

its a P229, not 239. Mistyped

That's correct: hammer, decocking lever, decocking lever spring, and decocking lever bearing.

Some guidance says that the sear should also be replaced when replacing a hammer, but that applies to replacing one DA/SA hammer with another DA/SA hammer. There is no reason to replace the sear when going from DAO to DA/SA.

And you can edit your original post to correct the mistake by using the little pencil and eraser icon in the middle of the three at the lower right corner of the post.

Thank you!!

Worked perfectly. Thanks for the advice