With only 5,123 examples produced in 1970, Mopar’s Six Pack 340 engine leans toward the very rare end of the musclecar spectrum. Those engines were split between the AAR ‘Cuda, with 2,734 examples, and 2,339 T/A Challengers making up the balance of 340 Six Pack production.

To find one of these engines available for sale is rare; even more so to find one with matching numbers. So when this barn find popped up on the ol’ eBay radar, we had to check it out. The engine wears the correct OB303458 serial number for AAR/TA 340 Six Pack production and has been sitting in a shed for an undetermined amount of time, evident by the prolific rust seen in the photos.

However, it does appear that the parts will clean up with a bit of effort and money, so maybe it’s worth it to take a look if you’re in the market for a truly original Six-Pack block and heads. The engine still wears the standard-size bores, so a cleanup will likely be necessary, but the meat is all there – it’s up to you to provide the cheese. We’ve seen much worse come back to life with a bit of TLC.

The 340 Six Pack engine has always been one of the favorites for Mopar enthusiasts, as they were factory equipped with a forged crankshaft, 10.5:1 compression ratio, and high-flowing “915” cylinder heads from the 360 Mopar. These heads featured revised intake runners to provide for pushrod clearance, big ports along with 2.02-inch intake and 1.60-inch exhaust valves. On top, an Edelbrock intake manifold and three Holley two-barrel carburetors provided the fuel and airflow. In addition, a dual-row timing chain and windage tray were installed to keep the bottom end happy.