1983 Pella lock needed double hung window

Thanks for posting. The lock body looks similar to the Pella 90-213, though this comes with a keeper that it seems your setup wouldn't use. Take a look, and let me know if you think this lock is worth a try. 

We unfortunately don't have another lock that might work for this application. The trouble is that you have an older design that isn't made anymore. Pella also never bothered to make an exact replacement. The 90-213 is technically a newer style, but it's so different that it won't be a 1:1 fit. 

In my personal experience, I have a high success rate for using the 90-213 on this window with little to no adaptation necessary. However that's not always a universal experience. Sometimes it's less than perfect, but considering the old style doesn't exist I've found that there's not much I can do about it. It's unfortunate, but that tends to be the case in general when dealing with Pella parts.

I am sorry to be the bearer of bad news. I really do think the 90-213 is the best option available, though not necessarily guaranteed.

This lock is unfortunately not made anymore. As suggested above, the 90-213 is the only replacement available. I recommend reading the posts above for more information, if you haven't already.