Under-latch/keeper for series 200 SH storm windows

I used windows furnished by amazing windows of New Orleans for my beach house after Hurricane Katrina. They are Series 200 SH windows and have performed well. The latches, the fixed keepers, have corroded out to the point where they have crumbled and disintegrated. As a result we are no longer able to secure the windows. Replacement of the windows will be well in excess of $6500 for the four existing windows. My problem will be solved with replacement keepers. Can you please help me? They were or from Showcase Windows ..... the P.O. # 50099 and Invoice # 35356. Have tried to access your catalog but can't seem to find the correct section.  Any assistance you could furnish will be greatly appreciated. Thanks Bill