Tailwheels. I think they suffered more abuse than what we gave them credit for; easy to replace a tube though. By habit or design I don't know but we never used tailwheels locks and the shimmying these things did on takeoff roll was enormous.
We were standing beside an 88 on a hardstand one day waiting for the old girl to warm up after starting when we heard a single clunk behind us. We turned around and looked toward the rear of the aircraft to see it sitting on it's newly broken tailwheel leg. It broke all on it's own, the aircraft not having moved.