I don't know if it's from an auto or not. Tip away kind sir.......
The engine we were swapping in came from a manual transmission jeep, so it came with a flywheel. When we swapped the flex plate over from the original engine, we used the bolts from the new engine, which are made for the flywheel. We didn't learn until we had the engine back in the car that the bolts for a flywheel are longer than the bolts for a flex plate. We had to disassemble the engine from the transmission to trade out to the flex plate bolts, otherwise everything would not go back together.
So, bottom line, transfer over the bolts from your original engine.
Good luck, it was a fun project putting the new engine in!