Mattsuzie, I had no warning that the timing chain was going to break, BUT I new it was worn and I bought a new chain,BUT I broke my foot and didn't get around to doing the job. My tach was working OK. My 300D dose have a double chain. I know that the 83-360SL had a single chain as I had look at buying one. I seem to remember that the 80to83 360 engine cars had a single chain, BUT I don't know that for sure.