Here's why:
* Engine variations: Even within the same model year, Chevrolet 305 engines could have different specifications.
* Balance Damper Types: There are different types of balance dampers (harmonic balancers). Some are internally balanced, some are externally balanced. These are not interchangeable.
* Bolt patterns: The bolt pattern on the crankshaft for the balance damper needs to match.
To be certain, you need to:
1. Identify the specific 1987 engine: Look for the casting numbers on the block and on the balancer.
2. Identify the specific 1989 engine: Look for the casting numbers on the block and on the balancer.
3. Compare the specifications: Check if the bolt patterns match and if the balance systems are compatible. You can use online resources or a parts catalog for this information.
Important note: It's crucial to use the correct balance damper for your engine. Using the wrong one can lead to serious engine damage.
