* Different Transmission Types: The Impala SS used a 4L60-E automatic transmission, which is a heavier-duty transmission designed to handle the significantly higher torque of the 5.7L engine. The 1994 Caprice Classic 4.3L likely used a 700R4 or a 4L60-E, but the 4L60-E in the Caprice would be a lighter-duty version. Even if both are 4L60-E, internal components and the computer calibration will be different.
* Torque Converter: The torque converter in the Impala SS transmission is designed for the higher torque output of the 5.7L engine. Using it with the 4.3L would be inefficient and could even damage the transmission.
* Computer Control: The transmission control system is integrated with the engine's computer. The Impala SS's computer expects to control a heavy-duty 4L60-E; the Caprice's computer is programmed for the 4.3L's requirements. You'd need extensive wiring and potentially a custom tune to make this work.
* Physical Differences: While there might be some bolt pattern similarities, there could be subtle differences in the transmission's mounting points or bellhousing that would prevent a direct swap.
In short, while the transmissions might seem similar at a glance, the internal components, computer control, and torque converter are all optimized for their respective engines. The cost and effort required to make this swap work would likely outweigh the benefits. A more realistic approach would be to rebuild or replace the transmission originally fitted to the Caprice Classic.
