Yeah, the tremec engineers told me the same thing until I took the car to them in Toledo OH and even they couldn't figure out the problem. I have spoken with Kevin (one of the TTC engineers) on a few occasions since my problems started and he couldn't believe my bell was out as much as it was... but it was. He told me that they used the same tooling used to make the t5 bells to make the tremec one and that it is made to the same tolrances as the factory bell, and that is why they say there is no need to index it if the motor is stock, but obviously its not always dead on. I went through a year of pure hell (it was so bad I almost concidered selling the car) all because I went with what everyone else told me. Very, and I mean VERY few people know how or have even heard of indexing the bell hosuing... hopefully I'll help change that so others don't experience the same thinsg I did.
Here's what I replaced to try and cure my problem which ultimately was only fixed by indexing the bell:
-replaced DS
-had stock DS rebalanced and new U joints installed
-repalced ring and pinion (yeah... that one hurt)
-replaced axles (this wasn't done to just fix the problems though
-replaced axle bearings and diff. bearings
- put in new differential (this wasn't done to just fix the problems though)
-replaced TKO input shaft bearing
-had tranny gone through by Bob Hanlon
-had to replaced blocker rings due to missed shifts due to the tranny problems
-replaced fluid at least 3 times
That's a whole lot of money to throw at a problem. And before anyone thinks I just through money at the problem know that I was in constant contact with D&D (they'll never get any business from me anymore), Hanlons (GREAT PEOPLE!!!), Eric Swarr (great guy), Bob Callaghan (old TTC rep), Kevin Ryan (TTC Engineer), and the list goes on and on. I did what these experts recommended and everything was done with the thought that the thing being replaced/fixed was the cause of the problem. Maybe now you can see why I'm such a strong advocate of indexing your bell hosuings. Its SIMPLE to do, all you need is a dial indicator with a magnetic base, a piece of paper to write down the readings, and a buddy to turn the crank over while you watch the dial indicator.
JFYI- for those wondering what problems I had they were as follows:
-rpm based vibrations (above ~4000rpms even in neutral)
-mph based vibrations (it would come on like a switch at around 65-70mph and vibrate so bad I couldn't see out the mirrors!)
-hard shifting, especially with high rpm
-grinding gears particularly 2nd and 4th
That about sums it up.