* Same Transmission Type: The transmissions need to be of the same *type*. For example, a TH350 (3-speed automatic) from a 305 could likely be used on a 350. Similarly, a 700R4 (4-speed automatic) or a SM465 (4-speed manual) from a 305 could likely be used on a 350. You can't just swap a completely different transmission type (e.g., an automatic for a manual).
* Torque Capacity: The crucial factor is the transmission's torque capacity. The 350 V8 generally produces more torque than the 305. If the transmission's torque capacity is lower than the 350's output, you risk damaging the transmission. You need to check the transmission's specifications to ensure its torque capacity is sufficient for the 350.
* Bellhousing: The bellhousing (the part that connects the transmission to the engine) must be compatible. While the bolt pattern may be the same between a 305 and 350, there could be subtle differences, particularly if dealing with different years or specific engine variations. A direct bolt-on is most likely, but double-checking is important.
* Year/Model Specifics: Even within the same transmission type (e.g., TH350), there can be minor variations between years and models. This is less likely to be a major problem, but it's worth considering.
In short: It's *likely* you can use the same transmission, but you must verify the transmission's torque rating and ensure bellhousing compatibility before attempting the swap. Consult a transmission specialist or a reputable repair manual for your specific vehicles to be absolutely certain. Using a transmission not rated for the engine's torque could lead to premature failure and potential damage to the drivetrain.
