Lock shoes - unsure what part number

The part you have here is referred to as a pivot lock shoe. To replace it, you'll need either the 15-178 or the 15-188. You'll need to compare the dimensions shown below to determine which of these is the correct replacement.

Take a look at the video tutorials below for instructions on how to remove/install them, if you have any questions.

Dimensions for 15-178

Alternate image for 15-188