TUBTAR is right on with all his (or her) info....Yukon is steller....742 case is the strongest, but most won't agree. I can only tell you from my experience with both 489 and 742 in a Tbrake 3000lb big tire 10 second car
He's a he. And though I like little kids and puppies , my feminine side is not all that large. :D
I also use a 742 case , though a crush sleeve eliminator gets the 489 in the neighborhood. My rationale was this......which case did they copy when they did up the aluminum cases ?