1b 7a 6b 3d 8a 7b 3b 9b 2b 1a 9a 7d 6a 8d 8b 4b 2a 6d 5b 5a 2d 5d 4d 4a 3a 1d *b *a
12 10 10 10 9 9 9 8 8 8 7 7 7 6 6 6 6 6 5 5 5 4 4 4 4 4 1 1
So there's 26 unique characters, so we probably just have to assign the right letters to these.
Surely that's not an english plaintext, frequency distribution doesn't fit.
We can try a bruteforce and see if something show up.