Check Gages Light Flicker
 

I have been having a small issue I need an opinion on. I have an 1987 S10 Blazer 4x4. 2.8L. When ever I drive in the city my check gages light starts flickering. this usually happens when it is at operating temp, during acceleration. sometimes running at city speeds. 30-40 mph. nothing really changes in the way the truck runs, and all the gauges read normal. I am assuming the this is either a bad sensor, or an Alternator on the brink of failure. Any help would be greatly appreciated.

I know the check gauges light will come on if a gauge goes out of normal range. If operating temp is high, or oil pressure drops too low. IDK if it will go off for voltage, usually there is a battery light but i'm not familiar with the older dash. With it flickering either something is on the brink of being out of limits or its just broken and detecting a false read.

My 91 4.3 4x4 had a similar thing until I changed the distributor. But it could be about anything.