[jamesroy9289]

I just took out a year old aftermarket tach and replaced it with a tach dash. But I realized that the rpm's are off when driving down the highway now. The tach reads about a thousand rpm higher than my aftermarket tach read. I have 4.10 gears with an automatic and now it says I'm doing over 5 grand going down the highway. Is there anything I can do to my tach or do I have to replace it with a new one?