Will 1994 c20 van engine and trans work for a 1985 Chevy truck?

No, a 1994 C20 van engine and transmission are highly unlikely to be a direct bolt-in swap for a 1985 Chevy truck. While both are Chevy products, there are significant differences between the two generations. You'd encounter problems with:

* Engine Mounts: The engine block itself might be different enough to require extensive fabrication of new engine mounts.

* Transmission Mounting: The transmission bellhousing and mounting points will likely not align with the 1985 truck's frame.

* Wiring Harness: The 1994 engine's wiring harness and computer system are vastly different from the 1985 truck's much simpler system. Adapting this would be a major undertaking.

* Drive Shaft: The driveshaft length and yoke sizes will probably be incompatible.

* Cooling System: Radiator and hoses may be incompatible.

* Exhaust System: The exhaust system would need significant modification or replacement.

While some parts *might* be adaptable with significant custom work and fabrication, it would be a much more complex and expensive project than using a more compatible engine and transmission from a similar-year truck. It's generally not a practical swap unless you have extensive mechanical experience and fabrication skills.