See how stretched the pin in the top of the picture is?
The funny part is, the pin was 6" long. It decided to stretch at the end. This was from my first year plowing with my 80 GMC. The one below it is the proper length pin, just worn a lot. The retainer "clip" is not my favorite by far. These pop out all the time. The large cotter keys with the bend in the center are nice, but I keep them as spares.

These are the pins I use to hold in the hitch pins (called lynch pins). The same most walk behind mowers use on the front casters. I've never lost one, or a hitch pin, since I started using them 5 years ago.

These are the shear bolts used on many 2 stage snow blowers. They should never be replaced with any other type or grade of bolts. Just getting "shear bolts or pins" won't do. I don't think there is a standard PSI shear strength. Each Blower is different than others. I saw an 8 HP machine stop dead in it's tracks, when it picked up a piece of 1/2" re-bar (re-rod, reinforcing rod, etc.) about 16 feet long. It wrapped around the auger, and stalled the machine. I mean it wrapped a few times around the vanes of the augers! With about 10 feet sticking out the front of the blower. My co-worker dragged it back to our maint. shop. Took him 2 hours to disassemble the font of the machine, and untwist that re-bar. If you've worked with re-bar, you know how hard it is to bend! The blower had no trouble, and the shear bolts were the proper ones. I hope they'd shear if my leg was in there!

More info on Meyer Plows: