Tach in 87 Ranger 2.3 Reading High

[velcro7279]

I have an 87 Ranger with the 2.3. After looking at and driving this truck for a while now I believe that it was assembled with parts from more than one truck. The VIN says that it should be a 2.0 2wd but it is a 2.3 4x4. Anyway, the tach in it reads about 400 RPM too high as near as I can tell. I am thinking that it might have been from a V6 truck. Is there a way that I can check this and change the way it reads if this is the case?

Steve