Sorry to hear but it sounds just like what happened to mine. Railroad track vibration is right on. I had it rebuilt at 125K. The pan was full of that gunk. Kinda reminded and felt like graphite to me. Anyway. i had a freinf of a friend do it for me for cost. Still ended up running me $950. It got a new HD converter, I busted the OD sprage in 3 pieces, and roached 3 bearings. He said he was amazed it didn't blow the case apart. I had an accumulator kit installed as well. It runnsgood and strong know. If you want to change the fluid inthe converter, pop the rumber plug on the bottom of the bell housing and rotate engine till you see a small plug. It will take a very long time to drain it. Very small hole.