Keep old key when replacing door catch assembly?

[panorama]

I can't open the driver side door from outside (works from inside). If you look at the picture of the part below, the thing that's broken is on the far right of the picture (little protruding lever like thingy).

The following part seems like it would fix it:

51-21-8-199-923-M9 Door Catch Assembly with Key, Left, BMW E36 3 Series, All (1992-99)



Question: Can I keep my old lock? I really don't want to have to have a separate key just for one door.

Would it be possible to replace just that metal lever? $170 seems steep just for the lever but if that's how much separates me from being able to open my door from outside then be it

Thanks for your help

[fastfredracing]

I am pretty sure, but not positive that you can swap your existing lock cylinder into the new door handle

[gimmeinfo]

is there guide to replacing this part? mine broke a while back and i found a guide before, but now i cant find it anymore.