The aluminum part is 25" x 5/8" x 5/8"
When I searched your site, a customer having a part with the same serial number suggested what I need is:
25" Series 370 Channel Balance Option 2430
I have no idea what Option 2430 is, or if he is right.
I downsized the pictures, but if you need bigger images, I can send them.
I don't know how quickly I learn, but 70 years ago I grew up on a farm with a wrench in my hand. But, the handyman who is fixing the windows is having trouble. I downloaded videos since then. Wish us luck.
Thanks,
Lyman