here's why, you have no idea what that shaft has been thru...and they are HEAVIER, and maybe you got an old shaft from a truck like mine, that drag raced off every light with 10k behind it and had 850 ft lbs, hammering that shaft all it's life...
Stl shafts only have a 3% rate-twist before they fail, which means if they have flexed or twisted 3% you are starting with a shaft that is compromised.....
You also do not know if that shaft is slightly bent, and are wasting money....
Just See your LOCAL driveline shop, if you have one, and speak with them, if they aren't sure, then ask me and i'll tell you what you need to know to tell them what they need know....
