2.9L 1986-1990 Cylinder Heads Interchangeable?
 

Are the cylinder heads for the 1986-1990 2.9L interchangeable? I know that there were changes through the years, but can you take cylinder heads off of a 1990 2.9L Ranger and install them on a 1986 2.9L Ranger? Also, what differences are there through the years?

Yes, they can be swapped 1986 to 1992

But you want 1989 to 1992 heads, later design was less prone to cracking

Read about the 2.9l here: Ford Ranger/Bronco II 2.9 liter Engines