That's interesting... Mine might be a tad longer, but it is the 5". I've got 3.73s as well. I think the issue is that the aluminum shafts are more sensitive to balancing than the steel ones are since they're lighter. If both shafts threw a weight, or are out of balance to begin with, the aluminum would be in deep **** relative to the steel one.
I talked to a few other gear heads today to get input, and since I've had mine to 120ish on many occasions, they don't seem to think it'll have any problem at the track. I'm just the paranoid type

 

what is the factory speed limiter set at????

 

was thinking i seen the ecsb is 1" longer wheel base and i thought they all had 2 piece but i guess not. i remember asking the dealership for a list of wheelbases and driveshafts and lengths but the guy showed me something around 50 different driveshafts that come in gm trucks. im the paranoid type to so ive been trying to get quotes on new shafts. they start to get pricey when you go 2 piece which really at our length they just about all recommend. you figure your locked in 3rd gear you turn the driveshaft at whatever your engine rpm is. critical speed on something that long is pretty low

btw i see you changed your name on here. every time i seen your old one i tried to figure out what it meant

something like 98?

 

wtf? they ******* snap? where do the snap at the rear? Does anyone make a bolt on drive shaft saftey loop for the GMT900's?

 

99.2mph and 99.4mph is the fastest I have been on because my truck still has its speed limiter!!!!

 

have 180,000 mile on my 1 piece, have had it to 141mph and over 120mph many times, get the vib at 100 too, its like a light switch, smooth, vibrates, then super smooth again. i have it speed balanced a couple time though when i first felt that common vibe, so maybe thats what has saved it.

 

120+ Mph on my reg. cab 09 4x4 z71

 

Going to bump an old thread because I have been talking to driveline people for the last few days. The general consensus is that in the driveline world its not recommended to make a one piece driveshaft over 68inches long. Some have said they would do 70-71 but that's right on the ragged edge. My drives shaft for example is 82in long. What I have come up with is if I really want to safely go over 100mph+ and not have to wonder when it will bite me in the rear, is to have a 2 piece drive line built and fab a crossmember to support the carrier bearing.

 

You have stock 82" 1 piece?? I'm running a driveshaft specialists 5" alum about 72" long and have spun it to 6200 rpm no problems

 

tiff youll probably be ok. I know 62nalide had a stock dshaft in his truck. I was in it when we did a few 140+mph pulls