Older Anderson casement window glaze seal dark brown . 3X8

Thanks for your post! The Andersen glazing bead you have reminds me of the 55-303 Andersen 3/8" Glazing Bead. While I am confident the shape is a match, you'll need to be sure to carefully compare the dimensions below.

The bead is available in white or terratone.

Profile view of 55-303