Here are some corner braces to replace your bent or missing ones on your project.
If you notice one or two of them have 67-68 chalked on them - that is to say that I took them off of a 67-68 truck. Quite honestly, I can't tell any difference between them and the others.
Price per pair is $22 shipped
However, if you want all of them it would be $100 for all 12 of them PLUS shipping