I have a club cab long bed with short tailshaft trans and carrier bearing.
I am converting to 518 and would like to know if anyone has done this and scored a used driveshaft long enough to make this work. Any idea what the longest one piece shaft in the wrecking yards might be?

no clue, but I can tell you that my 2006 Megacab cummins/auto has a one piece shaft that's a mopar factory/dealership piece. It's aluminum, about 5" or 6" in diameter, and VERY long.

vans have long one piece also--later ones are aluminum as well

Talk to your local Driveshaft shop

I know that the center bearings are needed after a ? length

An 04 quad cab Ram with a Hemi drive shaft is between 71" and 72" u joint center to u joint center. The shaft is laying inside a car and I can't get a good angle to see the exact measurement (darned bifocals). This aluminum shaft is 4" in diameter.

I also have some B Van shafts that are as long and possibly longer, and larger in diameter that I didn't measure. I figured a Hemi Ram aluminum driveshaft that is 71+" long at the joint canters should cover the question. Gene

Thank you to everyone for your replies. The two piece shaft that is in it now is a small diameter. Afraid the shafts and carrier bearing would not hold up long with the 440 I plan to use. Since Ma Mopar has a 6 ft or so shaft in the vans and trucks I see no reason I could not use it in my build, provided it is long enough.

Do a google search for “driveshaft critical speed”. There’s a ton of information out there on the subject of driveshafts and their design that you may want to peruse before you fab something up.