The '86 F150 I picked up today has the factory in dash tachometer. I think it's the first time I've seen this body style with it. Anyone know if it was a common option or not?

 

It was an option, I do not how common it was installed. I know the '81 through '85 has the wiring in place to install the factory tachometer by changing the printed circuit board on back of the cluster when the tachometer is installed. Other than that it is plug and play. The '86 should have the same setup.