Well, I was presuming you were going for a full d20 system before, but if you really want to simulate DF-style wounds, you could try the Mechwarrior 3rd Ed system.
In that game, you had a set number of dice for an attack, with extra power adding more dice. (Somewhat like World of Darkness/Vampire games.) Also like those games, getting a 6 meant you could reroll and add on to the total. Instead of "successes", however, you just add up the sum, and check the wound chart.
I don't have the chart in front of me, but it wound up being something like this:
0-9 - Does nothing. Too weak to even bruise.
10-19 - Bruises (the skin/fat?). Add +1 to all subsequent wound rolls. This stacks.
20-29 - Major Bruises. Add +3 to all subsequent wound rolls, and subtract one from actions that use this limb.
30-39 - Fractures. Add +5 to all subsequent wound rolls, subtract three from actions using this limb, and you have a major wound point, (more major wounds than stamina, and you die) that subtracts from all rolls.
40-49 - Limb destruction. +7 to all subsequent wound rolls, limb is useless, and take two major wounds. You start bleeding heavily, causing major wounds every few turns if you don't receive immediate medical attention.
50-64 - Limb explodes in gore. +7 to all subsequent wound rolls, limb is severed, and take four major wounds. You are hemorrhaging, and take major wounds every turn if you don't receive immediate medical attention.
65+ Ludicrous Gibs. Your entire body is either chunky salsa or ionized vapor regardless of the actual body part hit. Instant death. (Note, this game had rocket launchers and 80-ton war machines that could fire lasers literally capable of melting a ton of steel in a flash, and had weapons that read how many people it killed per turn, rather than damage, so these deaths were pretty common.)