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