Went in this a.m. to dyno and compare some tunes.
In 3rd gear truck had a vibration that started at 4200rpm, tried 3 times, same thing so we shut it down.
i have heard too many horror stories about broken driveshafts.

Mine has the worst possible setup for a drive shaft , 82" long aluminum, one piece. 5.5 in diameter, don't know the wall thickness, it's a monster

tried 2nd gear to 5800 rpm and only made 260 hp which sure doesn't seem right, don't know what's up with that.
traction control was turned off but dic had service traction control warning, and abs light was on.
don't know it that is an issue or not, anybody know???

anyone dynoed with a shaft that long??

oh, well , i 'll get a high speed ds balance done and try again.

http://www.pontiacracing.net:80/driveshaftspeed.htm

https://www.performancetrucks.net/fo...haft+resonance

 

That's too bad about the vibration. I would check the wheels first.