I just bought a 87 Silverado w a 700r4 the owner claims to have just freshened up. I see a new converter in there too. The problem is on the highway when it shifts to overdrive it acts like it is surging in between D and OD. it shifts firm all the rest of the time and doesn't always happen. Im not 100% sure its not in the top of #rd that the problem is as if I keep it in 3rd it almost feels like it wants to do it in the top of the gear. Anyone have any ideas? It will actually hunt between D and OD I guess you could say.