Searching for Dc/P27

The only markings on the sash recoil boxes are Dc/P27 and I am not sure who the maker of the windows was that were used in this Nanticoke prefab home that was constructed in the 1970's. I want to be able to replace all of the boxes as at least one of the cords on each of the boxes (both left and right) have been broken.
Can you help? The boxes themselves measure ~ 6 1/4" x 2 7/8" and are ~ 5/8" depth.

Thank you so much for your help.
Diana