Nope, they are different. You may also need to remove the ring in the rear of the crank, where the converter snout goes into the crank. My 5.7 had a NAG1 originally, and the 545 converter snout is bigger. It's easy to get out. I cut into it with a carbide bit in the die grinder till it was almost in two, then knocked it out with a chisel and hammer. The part number on my flex plate is 04736604AA, but check to see if it's the same for a 6.4.