The 3.4/3.8 engine blocks have the same. I think it was probably just Jaguar saving money. Copied the same pattern and just shortened it for casting the 2.4 blocks.
You'll know by the block height, 2.4 is about 2.!!!! shorter than a 3.4/8. As Brian said check the number. Another quick observation would be the carb mounting on the inlet manifold.