Bolts VS the U-bolts really has NO BEARING on if one
is stronger than the other.... if you look at how the
U-joint sits in the yoke you will understand... most
people dont realize that the U-joint sits in the yoke
OVER 50% of the diameter and being that its OVER 50%
it loads the yoke and NOT the straps or u-bolts..
the biggest trucks all run the strap type mounts...
I run a 1.19 60' and its with the stock type straps..
the fancy cradle cup covers are the WORST thing you
can use... they will bind unless you have almost zero
pinion angle..... but they look cool... all the strap
or U-bolt does is keep the u-joint from moving forward
and has almost zero load.. except for the friction
in the front yoke trying to slide a bit
EDIT
This is what I run... pretty cheap and its been working
14 years now... being you have no threads you have use the U-bots