This is neat, PFR did the research and compiled an unofficial list of sack leaders going back to 1960. In
the new unofficial rankings, Deacon Jones ranks 3rd in NFL history with 173.5 sacks. And Al Baker would be your
single season record holder with 23 sacks in 1978 (scroll down the page in the link for the listing).
Also officially, no player has ever led the league in sacks more than twice. Unofficially Deacon Jones holds that record with 5 though.
And finally, Dexter Manley's totals would go up 103.5 when you add the 6 sacks from his rookie season (when sacks weren't an official stat).