How strong are the OEM driveshafts? How hard can you drop the weight of your truck on them (rockcrawlers) without them snapping? Or will the u-joints go first?

 

Ummm - you dent the shaft and it's not long for this world.

It is CRITICAL that you keep the DS clear of obstacles.

The ujoints are equivalent to 1 tons - it is exceedingly rare to have them break.

 

So what about the rockcrawlers? Do they ALL run custom driveshafts?

 

Even if you have heavy duty ones built, it's still a relatively weak link. Comp buggies deal with it a variety of ways - first, they're really light, second, they keep the DS as short as possible, and offset the diffs way out by the tire so it's more likely the tire will lift it clear.

 

Many folks get the stock shaft re-tubed with heavier wall tubing for additional dent resistance.

 

Thats what high angle drivelines did for me. as for the u-joints toyota makes the strongest pretty much on the market. They can get to extreme angles and last forever if you grease them every now and then.