3520 Balances for my windows

Hello! I do recognize this balance, or at least some of its individual components. This is a very old style that used a non-standard combination of nylon fittings; specifically, it used the 19-039 top.

The question now is what the bottom is. There are a couple different options and I am not able to guess based on your photos, since the bottom fitting is missing. Would it be possible to see an undamaged version so that I can get a better idea of what you're working with?

I would also like to know how many of these you needed altogether. These will have to be a custom order so it's necessary to have quantity ahead of time.