You are really going to get a lot of mixed responces to this question.
My truck weighs about 3300 pounds, and I ran stock front inner and outer axles for two years with 180 ft-lbs of torque from the engine and a 510:1 Crawl Ratio with 35" tires.
I never broke any axle, and when I took the front end apart a couple of weeks ago, everything was in great shape.
In my opinion and experience, it all depends on how you wheel your truck, especially when your steering is near the stops. The greater the angle of turn, the weaker the joint becomes and the greater the probability for failure to occur. There were many situations when I had no choice but to peg my wheel all the way to lock and proceed, but I was very careful not to let the front axle get too bound up, and I especially avoided bouncing the truck, which from what I have seen other drivers do, is one of the most common ways of breaking a front axle. Having the wheels pegged and getting on the throttle so much that the truck bounces is definitely one recipe for axle failure.
I am now running 27-spline longfield outers with our new 10-year cromo inner axles. I did this because I've recently upped my engine torque in excess of 225 ft-pounds and I am now running much heavier 37" tires.
I am so certain that I will not break any front axle, that I have adjusted my steering stops to the maximum angle that the Toy front axle can turn. So I have maximized my chances of breaking an axle by increasing my available turning angle, but at the same time I have greatly decreased my chances axle failure by using much stronger axles.
lilbuddy just broke a 27-spline longfield up at this years Sierra Trek. He has a longbed 1st gen with 37" tires and a Dual Marlin Crawler. I don't know what he was doing at the time, but I am willing to bet that he had his wheels turned nearly to their maximum angle.
Once you understand what it takes to break an axle, you can then take the necessary steps to avoid axle failure. This is why I wrote an article about Birfield failure back in 2001:
Why do Birfield joints fail?Regards,
BigMike
