* Specific Models: A 2500 is a heavier-duty truck than most 1500s. The transmissions themselves are different in terms of size and strength. You need to know the *exact* model of both trucks (e.g., C2500, K2500, specific trim levels). The engine and transmission options varied significantly.
* Transmission Type: Even within the same model year and truck type, different transmissions were available (e.g., SM465, TH400, 700R4, etc.). You must identify the specific transmission in *both* trucks. Just because they're both Chevy 2500s doesn't mean they used the same transmission.
* Transfer Case (if applicable): If either truck is 4WD, the transfer case must also be compatible.
* Bellhousing: The bellhousing (the part that connects the transmission to the engine) must match the engine in the 1987 truck. Even if the transmissions are the *same* type, different bellhousings might be used depending on the engine.
In short: You need to identify the *exact* transmission model in both trucks before even considering this swap. Even then, it's not a guaranteed fit. You might need to adapt the bellhousing or other components, which requires significant mechanical knowledge and expertise. A mechanic specializing in classic Chevy trucks would be the best resource to determine compatibility.
