Good afternoon "Ford Persons". It has been a minute, but i love coming here to gather info. I don't know if there is a thread already asking this, but i couldn't find it. My question is rather simple. I have a '89 with 302, 5-spd (Mazda tranny-M5R2). A few years ago, I cracked the block and found a replacement but am only just now getting around to messing with it to install. While removing any working parts from the old engine to compare and re-use on the replacement, I noticed the flywheel has a different weight. The cracked engine had the extremely heavy flywheel with the clutch kit. The replacement engine didn't have a clutch kit, and the flywheel was extremely light. I assume the engine was for an automatic tranny. I haven't done a thorough investigation yet until i start to clean the parts. My question is, are the flywheels interchangeable? Also, is there a balancing issue that goes with the flywheels?