After bensons 3 the next ones best hint is what dave thinks about at the vault. ''what is the worse case senario'', its said during the day and in the bad ending.
I would say you can ignore that and focus on the worse case senario. I remember Grizz saying its harder to find on sal's route specificaly. But it is in the conversation with sal in all routes, think the reasons sals harder is he says it only once i think.
