My husband really wants me to install seatbelts in my new (to me) 56. Any advice on this? There seem to be a couple different styles of mounting, etc....
Yes, you should install them.
Several options.
You may have had seat belts originally installed. They were an option. Look for brackets behind the seat that look like the ones at the bottom of the attached info from the CASCO catalog. Other vendors have similar.
Also, Ernie Phillips has posted an article about a way to do 3 point seat-belts. It requires a bit of work.
Here is a link to that with pics and a .pdf at the bottom with info. https://www.dropbox.com/sh/t4e7nhtrnbcszj3/YunFyJVxuy