* Bolt Pattern: The bolt patterns *might* be the same, but this isn't guaranteed. You need to verify the bolt pattern (number of lug nuts and their spacing) for both rear ends. If they differ, you'll need new wheels.
* Axle Width: The 3/4 ton truck's rear axle will likely be wider than the 1/2 ton's. This will affect the wheelbase and potentially require modifications to the frame or suspension, or even new longer axleshafts (highly unlikely to be a direct swap). This is a major hurdle.
* Spring Perches: The spring perches (where the leaf springs attach) will almost certainly be in different locations. This means welding new perches onto the 3/4 ton axle housing or modifying the 1/2 ton's frame.
* Brakes: The braking system may be different, requiring brake line modifications or even a complete brake upgrade.
* Differential Ratio: The 3/4 ton likely has a lower gear ratio (numerically higher, e.g., 4.10:1) geared for hauling heavier loads. This will significantly alter your truck's performance and fuel economy. The speedometer might need recalibration.
* Shocks and Suspension: The suspension components (shocks, springs) will likely need to be changed to match the heavier 3/4 ton axle.
In short, while it's *physically* possible to swap the rear ends, it's a significant undertaking requiring welding, fabrication, and potentially specialized tools. It's not a simple bolt-on swap. It's much more likely to be a project for an experienced mechanic or fabricator. You'd be much better off finding a suitable rear end from a similar year 1/2-ton truck if you're looking for a straightforward replacement.
