HI Guys - need some help. I have a 66 F100 that came to me with a 1978 351M that was shot. I pulled it out and installed a 1966 289 out of a 1966 Bronco. The 289 didn't have a flywheel so I ligned up the 351M flywheel and it bolted right in. But when I took the first drive the whole cab/engine was really vibrating severely. I had a couple of mechanic friends look at it and they said it was probably the flywheel.

I just pulled it apart today and lighned up the new flywheel which is supposed to be for a 66 289, with the 351M, and the 289 flywheel is 1/2" smaller diameter all around. I don't think the teeth will lign up with the starter but I'd have to assemble it all together to see. Also, this flywheel is "externally balanced" and came with a bolt on plate. If I install this one do I install the plate (and if so where on the flywheel?), or leave it off?

Any help would be appreciated.