Quote: If it was in the motor /front trans area, wouldn't it vibrate with engine rpm and/or in nuetral?
it do feel some vibes but not as bad, but when you sit in the car in 3rd gear 35mph @1800 it feels like your teeth are gonna fall out of your head, when you go under the car and feel the rear housing, you can barely feel it, go to the trans mount area shaking like shakes more than an 1/8. it is so bad.
I had a cast crank 440 with steel balancing stuff on it. I've got a 383 with a shimmy stemming from the convertor hub being out of whack. Both of those deals you could feel vibrations at 35 mph. BUT, you could, (and I did ) race them. They were fine as far danger goes, just not too good on the bearings. Both of them had the exact same vibes in nuetral as driving. Your deal has got to be at driveshaft speed . If you go under the car, how hard is it the physically move the pinion snout around?, pretty hard. Now try moving the rear of the tranny around, somewhat easier. If there is a d/s issue even at the rear, its going to start tossing the tranny around. Its hard to diagnose from 8 million miles away, but when you keep saying its scary at 80 miles an hour, I find it hard to believe its engine rpm related. You would know it in neutral...
) race them. They were fine as far danger goes, just not too good on the bearings. Both of them had the exact same vibes in nuetral as driving. Your deal has got to be at driveshaft speed 
. If you go under the car, how hard is it the physically move the pinion snout around?, pretty hard. Now try moving the rear of the tranny around, somewhat easier. If there is a d/s issue even at the rear, its going to start tossing the tranny around. Its hard to diagnose from 8 million miles away, but when you keep saying its scary at 80 miles an hour, I find it hard to believe its engine rpm related. You would know it in neutral... 
