Here's why:
* Engine Mounts: The engine mounts are different between the Oldsmobile and Pontiac. You'll need custom engine mounts fabricated or adapted.
* Transmission: Even if the transmission is the same type (e.g., TH400), the bellhousing bolt pattern likely differs. You'll need a bellhousing that matches both the Olds 455 and the Pontiac transmission.
* Exhaust System: The exhaust system will need to be custom-made. The 455 is a larger engine and will require different routing.
* Steering: The larger engine may interfere with the steering components, requiring adjustments or modifications.
* Bodywork: The 455 is a physically larger engine. You might need to modify the firewall or inner fenders to clear it.
* Driveshaft: The driveshaft will almost certainly need to be shortened or lengthened to accommodate the different engine and transmission dimensions.
* Wiring: The wiring harnesses are different. You'll need to adapt the Oldsmobile wiring to work with the Pontiac's system.
In short, this swap requires significant mechanical skills, fabrication abilities, and specialized tools. It's not a project for a beginner. While achievable, it's a complex and time-consuming undertaking. You'll likely need a professional mechanic with experience in engine swaps to help or even do a majority of the work.
