Question for 1 piece driveshaft dudes

[Molberg]

How many of you are experiencing failure/vibration? Contacted a local reputable driveshaft builder, and he told me the length is too long for one piece. (Even with a 4" tube) said it will be fine as long as rpm doesn't exceed 3000. Lol. No good to me. Worse if I ever go with an overdrive unit. The more I read about it... Seems he's correct. At critical speed the shaft may bow and "whip" around. I did this conversion to a '72 gmc years back. Didn't notice any issues. Link below to a well known manufacturer... With a calculation table. Won't work according to this.
http://www2.dana.com/expert/wc.dll?hvtss~Decrits~

[Molberg]

The measurements I ran were for a long bed. Short bed should improve drastically.

[gottrucks]

Many years ago, I had a '72 GMC shortwide. Originally it was a six cylinder and three speed. I drove it for a long time in that configuration with a one piece drive shaft, and then even longer with a 327 mounted in the six cylinder location with no issues ever. I eventually switched to a 350/350 in the v-8 position and went to a 2 piece at that time. I don't remember how big the original shaft was, but it was definitely big.

[airbrushguy]

My '71 C10 longbed came to me with a 250 6cyl and one piece driveshaft. Never questioned the owner about it but he bought it new and didn't seem the type to have changed it.
As before I changed to V8, it still doesn't vibrate.
Is there a chance this was a stock setup?

[mcbassin]

I have a one piece in my truck. My truck is a SWB with a 4.8/4L60E. My driveshaft was made at a local place and balanced. My drivetrain is smooth up to about 85MPH then I get a vibration. It feels like it's the driveshaft but I have no way to confirm it.

[Andy4639]

I had the 6.0/4l80e combo installed in my 71 LWB over a year ago. Drove it on last years Hot Rod Power Tour 3600 miles with no issue's ran 80-90 MPH sometimes. I do get a noticable sound out of it at that speed but I think it's because it's hollow. Mine was built by a drive shop locally. I don't think you will have any problems.

[gvnick]

Aside from a 1 piece being arguably too long for a LWB truck, I would think you would have interference with the trailing arm crossmember. Because the pivot point is so far forward of the crossmember, I'd think you would hit the tube on the crossmember at full bottom or top out. My opinion.