Are all stock driveshafts of the same quality?

GENERALLY the weak point is the U joints, not the shafts. But there is a TREMENDOUS difference in quality between U joints. When the "import parts" nonsense really got underway in the '80s, we used to see a lot of these "chain store" joints come in broke/ damaged/ wore out. Back then we sold stuff like Precision and Spicer, some Borg-Warner, and Rockwell, before any of e'm got "Chineseo'd"

Also, if you are REALLY pushing the limits, you want a cross with NO grease zerk, because it reduces strength.

On the other hand, my old '70 sixpack RR only had 2 U joints replaced in it's life of 140,000 miles.