No, a 3.8L transmission will generally
not bolt up to a 5.0L engine without significant modifications, if at all. The bolt patterns on the transmission bellhousing and the engine's flywheel/flexplate are different. Even if the bolt patterns *were* the same, the input shaft of the 3.8L transmission may not be compatible with the 5.0L engine's output shaft. Internal components, like gear ratios and torque capacity, would also likely be mismatched and lead to failure.
You'd need an entirely different transmission designed for the 5.0L engine. The specific transmission will depend on the year and model of both the engine and the vehicle they were originally installed in.
