From the P22 manual. The bolt you are looking for is marked in red. There are actually 4 bolts in the assembly mounting. The bracket in the drawing is truncated off but you can see the ear that corresponds to the bracket in your picture.
M10 1.5 x 40 GM PN 1159844.
Unless it is a really odd size you can probably find one similar at any HW store that has an extensive nut/bolt section (my local Ace Hardware has a section called the nut house for most of this stuff) just be sure to get the same design bolt head and hardness. If it is a flanged bolt be sure you get one that is the same. You could adapt a bolt/washer combo if you need to as it isn't a critical location.
The P22 manual is invaluable for finding part and assembly drawings like this. Even though most of the part numbers are obsolete, it at least gives you the location and spec for the part. There should be one linked on here someplace if not let me know and I can send a PDF of it.
[This message has been edited by Mark_j (edited 07-16-2022).]
