Any thoughts on this shakin' problem '94 GT

[Venom351R]

What exactly goes wrong with the balancer that makes it vibrate?
Does it start to loosen itself from the crankshaft, or something? What should I be looking for when I check it.

The rubber on the inside of the ballancer starts to come out, thus throwing off the ballance of the ballancer and causeing a vibration. Sometimes the ballancers get so bad they shake them selves apart and in some cases can cause motor damage.

 

[jmuva44]

I used to have a shake that would only happen at about 35 mph. Did a transmission fluid flush....went away. But then the tranny crapped on me and I had to get it rebuilt.

 

[Slow5.0]

I forget to tell you guys I rev up for like 20 sec with open headers (because I have to take mufflers off two bolts on front od LCA is pain in a$$ so I take h-pipe and see how sound with open headers , meybe that can cause some problems , I put exhaust like before, I still can't find whats wrong , AND this weekend I going on track test all this new mods and I wanna find what cause vibration before saturday