Lindsay Lohan & Heavy D -- Morgue Buddies

Lindsay Lohan and Heavy D are closer now than they've ever been before, TMZ has learned ... because they're both serving serious time at the L.A. County morgue -- for very different reasons.

Lindsay has been working like a dog at the morgue for weeks -- and now we've confirmed ... Heavy D's body is currently being stored in the same facility.

Lindsay's morgue work does entail some corpse contact -- but sources tell TMZ, the actress will NOT come face-to-face with Heavy D's cadaver.