Hello. I just got back from the mechanic...the problem I'm having is TREMENDOUS vibration when the car gets to 3rd gear. I tried to steer the mechanic towards the Harmonic Balancer issue, but after a quick test drive & poking around under the car with the pry-bars...he'* convinced the problem is the ignition pack. At this time, he'* certain that 1/3 of it is gone & because of this the engine has a "dead misfire" in it. What do you think? Sound logical?

It could happen.

Would also be waay down on power.

yep its exactly that, a miss firing cylinder.
I had this problem, its awful.
You know what fixed it?
a new computer
junkyard- boner- replace

ask him if he checked the coil pack with an Ohm meter.