I want to install an alarm in my 1991 300D. I often work 11 hour shifts at one of my jobs, and it makes me a little nervous to leave my car unattended in a parking lot so close to a movie theater for such a long time. I did a search on this site for any pertinent information, but I was unsuccessful.

Would it be feasible to install a factory alarm? Would that option be excessively costly? If so, I would consider installing an aftermarket system. Does anybody have any recommendations?

Thanks everybody!

__________________
Ben

The MBs:
1976 300D (W115) - 330K and still going (sort of)
1991 300D 2.5 Turbo - Sold at 221K
1983 280SEL - Sold at 206K
1981 300SD - Sold at 232K