WWII MBT T3 Trailer Article : Removing Cotter Pins

At the start of every project you will need to start hitting nuts and bolts with penetrating oil for rust. This usuall takes a couple of squirts on all bolts that are rusted over.
On the MBT and T3 trailers, there are castle nuts with cotter pins holding them in place. These can be frozen and/or very brittle. First, straighten the cotter pin out with needle nose pliers
Now, take some snipes and clamp down on the top or hook part of the cotter pin and hold tight without cutting.
With a good grip on the snipes, take a hammer and pound the snipes so the force on the cotter pin comes flying out.
If the cotter pin breaks, then follow the same steps with each piece that remains in the hole. If needed, swtich ends, and try from the other side.
With rusty parts, you can still have issues with breakage. If the cotter pin breaks, thus no grip with the snipes, then use a small punch or ice pick and try and tap one side of the cotter pin out where you can grab it.
As a last resort, use a small drill bit, and drill the cotter pin out. Be sure to use a smaller drill bit than the existing hole.