My friend has 71SS Camaro.To the right of the heater core cover is another little cover to something. This cover is about 3x4inches.There is only one wire going in.Inside this box the wire is connected to a metal strip that resembles some sort of contacts.I know my description sucks, but any info is helpful in finding out what it is.

Could be the Temperature switch for the Transmission Spark Control system.

A transmission mounted switch, actuated only in high gear, and this temp switch, closes when eng temp is above 82*F, are wired in parallel with each other to activate distributor vacuum via a Combination Emission Control (71-72 in my book, only goes up to 72) system solenoid activated during high gear deceleration against the carb throttle. This keeps the engine at a higher idle during decel only in high gear.

Maybe, just a guess.......

Was the temp switch used with automatics or 4-speeds?My friends car is a stick-shift.

Both. A switch on the trans linkage if manual. An auto used an oil pressure switch.