I have a C6 4x4 Transmission with 0 miles on it that fits 351M, 400, 429 and 460 engines. The transmission was built to handle a mild built 400 in a 79 F-250. I have since picked up an NP435 and am using that instead. There is a new torque converter with drain plug that goes with the transmission. It does not have an extension housing on it at this time. I don't know where it is. I am asking $700 for it because thats what it cost me to have it done. Feel free to email me with any questions.