The set has been in storage since 1999 in a box. I have not tested the part and cannot state any warranties as to if the set works or not as I do not have anyway to test it. I can say it was working when it was in the car at the time of removal. I did notice one of the copper trails on the edge of the circuit board next to the clock to be frayed and it will need to be soldered.
Otherwise, I saw no other issues. This 1978 Pontiac Grand Prix Instrument Cluster set is in my opinion in overall very good condition for its age, extremely rare, extremely hard to find in this condition and would definitely be an asset to your 1978 Grand Prix restoration project. Please view the picture and make sure the part is the correct application.