I've never seen a working factory alarm system on a C3, and my '76 is no exception.  However, after my brother had his daily driver (not a Corvette) stolen, it made me want to protect my Vette a little more.

It doesn't matter what kind of alarm system you have on it.  If they want it, they will take it because they are professional car "booglers."  Now, if you had a LoJack on it the police can track your car, you get it back and the chop shop gets busted.

Mine werks, if ya wanna come down here and check it out!

The switch in the fender would work for a kill switch, but...they pop out pretty easily, and most scumbag thieves will pop that first anyway.

A kill switch can be put just about anywhere, but, with an HEI ign., all you need is one jumper wire, and it's running.

The best deterent to a wanna-be thief/joyridin punk is a visable steering wheel/brake/shifter lock. Those take time to get off, and thieves don't like hangin around for too long.
The steering wheel locks I have go around/thru the steering wheel, and around the brake pedal. Granted, you can saw thru the steering wheel, and get the thing off, but, how long would it take? Plus, on my '74, or the '85, with the wheel tilted all the way down, it's almost impossible to get in there to saw it anyway. Most thieves are gonna look for cars that are the easiest to get, unless they are in the "Gone in 60 Seconds" game. Those people don't care what it takes...if they want it, they're gonna get it.

Ask Anthony(ten15)...he's a auto theft recovery officer. He'll know the best way to keep your 'Vette YOURS.

Mine works too but only a horn sound when the hood, doors get jarred. Take  Joel's advise with the steering wheel lock.. If they want it they will haul it off.. O'look Joel has a new signature picture...Nice

Yeah, I know nothing is a guarantee.  I was looking for a deterrent.  I do have a Club for the steering wheel which I use, but I wanted additional security.  Disabling the engine is the best I could think of.  If it had a seperate coil instead of an HEI, I would just take the coil wire off when it is parked.

Pulling the power wire is too easy.  A decent crook will spot it in a second.   You can splice into the tach wire under the dash where it cannot be seen, and add a switch to ground the tach wire.  When grounded it won't start. and it's not easily seen.