I swapped original 5.0 for 5.7 GM crate engine in 1996 silverado 1500 does the PCM need to be recalibrated?

Yes, absolutely. Swapping from a 5.0L to a 5.7L engine in your 1996 Silverado 1500 requires PCM (Powertrain Control Module) recalibration. The 5.7L engine has different parameters for fuel injection, ignition timing, and various other sensor inputs. The original PCM is programmed for the 5.0L and won't be able to properly control the 5.7L, leading to poor performance, drivability issues, and potentially damage to the engine.

You'll need to either:

* Get the PCM professionally reprogrammed: This is the best option. A shop with experience in GM vehicles can reprogram your existing PCM or supply a reprogrammed one specifically for the 5.7L in that year and model of truck. They'll likely need the VIN to ensure correct programming.

* Use a replacement PCM pre-programmed for the 5.7L: This is another good option, but finding the correct PCM can be tricky. You'll need to ensure it's compatible with your specific truck's year, model, and any additional options (like ABS, etc.).

Don't attempt to run the engine with the original, unmodified 5.0L PCM. It will likely run poorly at best and cause damage at worst.