I'm hoping can tell me if one of these is an 860/861 escape bridge. They came together with a heap of other parts, the one on the left is about 1967, the one on the right about 1968.

Is the one on the right an 860/861 bridge? it's got a larger cut-out for the balance, possibly because they were different/larger than a 320/321?

 

Looking at online 861 and 321 photos, I think so. You can also check through the serials on the other side, I think.