Have been contemplating adding an aftermarket alarm to a 1978 450sl. Was wondering if this is a good idea, that is, would it conflict with existing electronics? Would the keyless entry work with the '78 vacuum lock system? Would there be any special installation required? Or is this something any auto electronic shop can install?

Has anybody had any experience adding an an alarm to this model, and if so, success with any alarm brands/models, what to look for -- or avoid, etc?

Any insight is appreciated...

Brian
1978 450sl; 126K