I got an email from shredeagle asking if the tachs I am selling would work in his 4 cylinder Eagle. Since the F150 tachs only work with 6 or 8 cyl engines, those are not an option. However, I did a little research and found the Ford Rangers from the same era came in 4 or 6 cyl options. The tachs are very similar in appearance and wiring, and can be switched from one engine size to another by adding an extra ground wire.
I went to the local junkyard and found a 1989 Ranger with a tach (pictured below). I came home and tested it out on my 6 cyl Eagle, which required an extra ground wire, just like the F150 tachs need an extra ground wire to work with an 8 cyl engine. It tested fine. Although its not as close a match in the style of the numbers as the F150 tach, it should still look good for anybody with a 4 cyl Eagle that wants a working tach. And it even has a redline zone, starting at about 5500 rpm!