I read a book about 20-25 years ago that I'm trying to remember. It started with a spaceship crash. The story mostly took place on a lifeboat after the crash. Aliens were the pilots in this universe and at least one (maybe two) was on the lifeboat. They were taller than people, and seems like they had three fingers and were covered with fur. The plot was a mystery, I think somebody was killed in it. The thing that struck me was that there were three classes of people in this universe, elderborn, arbites and simples. If anybody remembers this one, I'd love to know what it is.