So I bought an 05 3i 2.3L for $800 with a shot engine (rods kicked through the block in 3 places). Then I bought a slightly damages 2.3 from a junkyard to make a good one out of two. Then came my problem as I am reassembling the junkyard engine (after a complete teardown) I come to my timing chain and gears. The engine out of my car has a finer tooth chain and gears than my junkyard engine has. I also notice that my heads are slightly different. I call my local Mazda dealer and all they can tell me is yes Mazda used two different chains in that year. I didn’t even want to ask about the difference in the heads considering they they were little help to start. My question is has anyone come across this before or does anyone know why these parts are different. I have also figured my junkyard engine is from an 06 if that makes a difference. Banging my head against a wall for the time being. Any ideas please let me know.