I have a 68 camaro with a small electric/condensor unit factory/dealer installed
(riveted) on the wiring harness holder on the firewall. Anyone seen this before
and know what it is for? The only thing I could come up with would be an engine
compartment light on the hood?

Not sure how to add pic.

If it appears there is an orange wire running through it, it could be a noise suppression filter for the blower motor.

What does it go to when you follow the wire? Condenser is another term for capacitor. Used for noise suppression as Everett#2390 said and,on point cars,to soak up the spark when points open as not to burn the points or at least to keep the burning to a minimum. Without a capacitor checker you can test it for a short using an ohmmeter between the case and the lead. Since it is used in a 12 volt system it is highly unlikely that it is open. Just not enough voltage to fry it. Usually.

Thanks for the info. I have no electric knowledge. I called it a condenser for lack of another term to use. It has three wires, black, blue & green, all cut. No wires are hooked up to it. The unit has plastic sides with a metal top. The part number on top is 396157 and has the company name "Little fuse Inc.' on the top. So, maybe its an extra fuss/inline fuss for ???? The car is a plain option car, with a lot of dealer installed ones like rear spoiler, hood pins, drag race pulls on subframe, wood wheel(?). Just trying to figure what else they could have possibly had on it. Thanks again.

Could be a power conditioner for an aftermarket radio.

In the early time period, the mechanical voltage regulator, ignition point set, any switch, generated spikes in the power source, hence, speaker(s) reproduced the spikes as a .25 pistol shot. Sometimes blew out the speaker cone.