Sorry Duck...I found the little bag labeled "Glock Rear 6.5mm" but it had an adjustable rear in it. I am guessing my brother swapped it with the rear on his 35 last time he was here.
I may have one in my parts bin. If so you are welcome to it.
Looks like they are in stock here as well. Let me check my parts bin before you order one.
Glock Fixed Rear Sight, Steel, 6.5 mm, White
Another