Where can I find this crank?
Thanks for reaching out to us! This looks like a folding handle. The 39-205 comes to mind. This is designed to fit an 11/32" spline. Take a look at the specifications and see what you think.
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The black piece shown in your second photo can be removed so that you can install the new handle, yes!
It should just pull off as they're usually pressure fit. If it doesn't, look for a set screw underneath the black piece. You may need to unscrew that first if there's one.