Looking straight on (see those teeth where boards join up, you might even see the screwnail that was in this board)
It really looks like these sills are comprised of two boards. One is kind of what the window sits on, then there is a board 1.25 inches think by 3.25 inches deep (3.5 at the bottom, so a little flanged) that is attached to the other board, via screws.
I just need to get these done before we get too much wet weather! Appreciate any ideas. Hopefully in the Spring, I will replace them.