I have just completed a rebuild of my two speed from the engine to the rear. If you have oil in the lines from the inboard side it is probably from the seal located in the "pancake" assembly as was mine. Also if you have oil on both sides of the diaphragm your diaphragm is shot. In my line rebuild I used air brake line and new fittings all the way. I removed the old lines and took them to my local "big truck" shop and they duplicated them using new fittings as well. While not traditional it will guarantee no problems in the future. This stuff will not corrode or collapse.The original copper lines had rubbed against the frame and were paper thin in places. If you want to stay traditional go to your local hardware store and buy new tubing for your repair. The air brake line was actually cheaper than copper tubing,it is about $2.00 per foot for 3/8 diameter. Good luck and hope this helps.

JMH