What is it and can I do away with it?

 

It's a reservoir for your cruise control. That is, if you have cruise. Actually, it should be behind the bumper on the passenger side.
cm

 

semi-right. it is a vacuum reservoir. think of it as the cap to your entire vacuum system. if you take it out, your heater/ac will default to defrost mode (your blender door is vacuum controlled) and other vacuum operated things on that line will malfunction. better idea to relocate it.

 

I was asking because the car was in a minor accident before I bought it and its cracked and. You can hear it whisle lol so I guess I have to go snag one jy and figure out a place to put it instead

 

jakbob -
Thanks for the extra info; I didn't realize it also moved the blender door. Maybe that's why my a/c didn't work very well before I fixed the broken line.
cm

 

no problem. best way to think of it is take a straw, and put your finger on the end while you are trying to suck air. that vacuum that is created is what works a lot of things on your jeep (even the heater valve on mine).