Wenco windows
Thanks for reaching out! This pivot shoe is a match for either the 17/32" thick 15-178 or 1/2" thick 15-188 Pivot Shoes. To determine which of these is the correct fit, you'll need to double check the dimensions on the existing shoe.
I believe the zinc piece you are referring to is the pivot bar. These shoes don't typically use u-shaped pivot bars. They are most often used with something like the 26-226 or 26-352.
Carefully look over each of their dimensions and compare them to yours. See if one of the installation hole placements on them is a match.
The diagrams for each of the recommended parts can be viewed directly on the website.