I created a version of the thief I called the Knave some time ago for Labyrinth Lord, and now have a version just for 3LBB OD&D and 0e clones like S&W White Box. This version is much simpler, I’ve pared down the skills list and made the skill checks d6-only. I’ve also replaced the standard ‘climb sheer surfaces’ with a grappling hook skill. Traditional D&D thieves were never meant to be combatants, I’ve taken this idea a bit further with a couple of defensive fighting skills. Click on the image below for the PDF. Feedback welcome!
Incidentally, the font is a free (GPL’d) one called Universalis ADF that is a close match for Futura, the font used in many old TSR supplements.