drivetrain vibration and other questions

ive been getting some vibration from what i think is the driveshaft (NOT SURE) since i added 373s...it vibrates once i hit 100+ mph on the speedo (im actually going less since i didnt fix the speedo when i did the gears...anybody know how much is it really off?)...also my shifter vibrates like a mofo...anybody know how i can fix this vibration prob and know what i can do to make the shifter vibrate? the shifter has no type of spacers or gaskets whatsover so it might need some...let me know guys...thanks

p.s. .....im gonna head to the track very soon with darkhorse5.0 and i REALLY wanna get rid of these vibration problems
 
alum DS. Your old DS might have been a little out of balance, and the increased rotational speeds (reaching closer to the DS's critical speed) have exacerbated an imbalance issue.

You can play around with indexing your existing DS or having it dynamically balanced, but the Alum unit is likely the fix.

Good luck.
 
Alum d/s...

Don't delay these get more $$ almost daily...

I tried to delay and change things, even went through the trouble of having a buddy of mine pick up a donated d/s and ship it to me for me to put it on my car, well it was the d/s all along so now I was out a couple months of driving, the cost to ship the donated d/s and the FMS one went up in price while I was doing this...

Just get the alum it is worth it for the hassles alone...