Wellllll...... if you realllllllyyy want optional damage rules.....
The old 3e runners companion book came with optional damage rules that included limb, brain, and organ damage rules.
Which, if you really fucked up on the resistance test, could lead to early retirement, even if you survived.
"Ok Tim, last game you took a deadly wound right? (10 boxes), Ok, roll bodyx2 Vs a target number of 10... oh no successes? Ok tim, roll 3 dice, tell me the numbers. Great news! You lived! You just have a blown off left leg, a blown off right arm, no eyes, and moderate cognative imparement! Don't worry through! For 4 essence, and $750,000 you'll be good as new! Oh you're a mage...."
Its all fun and games.... until you end up blind and missing a liver....