I read through your ZF5 install thread. Specifically:
All right, so the shifter ordeal is solved. But the sh*t soup keeps getting thicker. Fired her up to get it moving, and that thing rattles like it's trying to disassemble itself. My guess is the flywheel that I used in the conversion has 7.3 weights on it (Flywheel is for a 90 so all the clutch parts match). I did notice the flywheel had a weight of some type on it that my original one did not. Can I put a 7.3 harmonic balancer / counterbalance on the front to balance it out? Or have I got to start all over again?
My original transmission that was in here was also solid flywheel, I know they make noise. This isn't noise. This is shaking. It feels like it's going to throw the trim off of the radio bezel.
Yeah, gets worse with speed; but it's still pretty rank at idle
You mentioned you had the knocking before the tranny swap, but I wonder if it could be two unrelated issues? Does the knock that's happening now sound and act the same as before?
I could be totally off base, but it sounds like you may have the engine very out of balance. With these engines being externally balanced, ideally you'd want to take both the new and old flywheels to a balance shop and have them matched. It sounds like that was what had been done to the used flywheel you picked up since you said it had some weights on it. It may have just been bad luck that the new (used) flywheel is "balanced" near the opposite of what you'd need it to be.
Or, another thing to think about. I know the SMF kits for the 7.3 come with bolts because the bolts for the old DMF wont work with a singe mass. I'm not sure though how that works when swapping from a t-19. Do you have any play in the flywheel with the clutch disengaged?
Sorry if you've already covered this. Just trying to throw some ideas out there.