Winchester model 59

12 gauge shotgun I need the part that holds the shells in the tube...I think its called a shell latch ?

I want to make sure I'm asking for the right part at the gun parts places I will call.

go to the www.e-gunparts.com website. They have most parts for your gun listed with prices. If you need it you can purchase a diagram and complete parts list for $1.50. Their customer service is usually very good if you describe what you need, they should be able to figure it all out for you.