I was going to go with the 5.9 to Allison 545 but then I found out it could olny top out around 70 with 3.54 gears so thats a no , then I thought go with a 5.9 hooked to a MT 643 but I dont know what the top speed on it might be. I wouldn't mind getting the dodge version with there auto hooked to it and get it built but I want a 5.9 with a p-pump and the dodge versions are very difficult to find. Can any body help me out here?