That is not true "back in the day" when they used those DAMNED alloy sprocket hubs with nylon teeth. I can still remember we replaced a sprocket on my buddies Chev 350, then later he did some other work to the engine (don't remember what) and the sprocket, with less than 40K on it had worn nearly to the aluminum in places. I have seen FEW chains jumped with all metal sprockets. Most were because of these damned nylon ones.