5hutyAewDs9BsUqVh1Nivythf49VvEzGXpDYj37ZLtDxdDyXN7D
how would you even decode this to my real key?
But it isn't the real private key, he has replaced part of the key:
5hutyAewDs9BsUqVh1Nivythf49VvEzGXpDYj37ZLtDxdDyXN7D
Hence the " 44/51 or ~86% (assuming 7 hidden and 51 total)" comment by shorena.
It is more of a security by obscurity argument to transform a portion of the key. It isn't a valid key of course with the substitutions.
If you are looking for a private key that has a replaceable prefix it decreases the search space dramatically and isn't safe.
edit: You can obviously do as you wish, but be very careful and be sure to understand the ramifications of what you are doing.