* Year and Model: Rear ends (also called rear axles) vary significantly between years and even trim levels of trucks and vans. A rear end from a 1970s Chevy pickup will almost certainly *not* fit a 2020 Chevy Express van.
* Axle Width: The distance between the wheel mounting points on the axle must match the van's chassis. Truck axles are often wider than van axles.
* Spring Mounting Points: The location and type of spring mounts (leaf springs, coil springs, etc.) need to be compatible. A truck's leaf spring setup is unlikely to directly fit a van's independent suspension or different leaf spring setup.
* Brake System: The braking system must integrate correctly with the van's braking components.
* Driveshaft Length: The driveshaft connecting the transmission to the rear end needs to be the correct length. A mismatch will cause binding and damage.
* Differential Ratio: The gear ratio in the differential determines how many times the driveshaft turns for each revolution of the wheels. A drastically different ratio can negatively impact performance and fuel economy.
In short, while it *might* be *possible* with significant modifications in *some very specific* cases (e.g., same-generation trucks and vans with very similar chassis), it's highly unlikely to be a straightforward bolt-on swap. It would almost certainly require extensive fabrication, custom parts, and a deep understanding of automotive mechanics. Don't attempt this unless you're a very experienced mechanic.
