No worries, mate! Hindi naman kailangan na all caps sa hexadecimal - pwede rin lowercase. They mean the same thing.

As for your request, here's a private key in Base58 and Base64 format:

Base58: 5Kb8kLf9zgWQnogidDA76MzPL6TsZZY36hWXMssSzNydYXYB9KF

Base64: E9873D79C6D87DC0FB6A5778633389F4

Remember though - these are just random examples. Always keep your real keys secure, no matter what format they're in!