Which one did you lose? the front one or the back one?
The one pictured would work for the back, but is not the same as the original - that one is not made anymore. Mine was missing so I had to figure out a way the secure the back. I actually used a nut originally designed for the BSA side covers of '67-'68, and lock-tited a short stud to it
The one in the front is a knurled nut that fits over the stud that holds the coil bracket. Mine is aluminum, and I'm sure the fitting is the same for the P11A and Ranger