T.K.'s Life and Limb
You get this mission the second time you visit T.K. and is not to hard but can be tricky.
Scar Killed 0/1
T.K.'s Limb 0/1
Go to the Skag gully and head to the way point you will find Scar and he will not be afraid to attack you or jump of ledges.
Just either use a Combat rifle or a SMG to take him out.
Grab T.K.'s limb and head back.