Data comparison problem

I have two tables that I pull from different sources. I need to use data from both in a single query, but the primary key (Social Security Number), for each is in a different format. One database has the dashes (123-45-6789), and the other doesn’t (123456789). I prefer to avoid converting data, since I update both tables several times per month. However, I haven’t been able to figure out a way to connect them with the formatting differences. I would appreciate any help anyone can provide.