The harmonic balancer and the flywheel are externally balanced, you will see that right away. If my foggy memory serves me right you will notice the 400 had a different setup for the freeze plugs on the side of engine, don't remember exactly (it's been a LONG time )but I think that they only had 2 on a 400 and maybe it didn't have freeze plug under engine mount.


Tommy
59 apache 1/2t
261 short stepside