i almost never post on here because i hate getting in pointless arguments that go nowhere with people unable or unwilling to understand. anyway.. i agree with you on making a known weak point in the driveline . u joint strength i cant help you with, other than breaking a few with a torque gauge. i got an adapter u joint for detroit 5380 to 1410 off ebay that was n.o.s from the 60s or 70 in it had a paper in the box about picking a ujoint to be a "fuse" in the driveline.i looked for the paper, and looked in my ebay history to find the joint but it was too long ago. i was going to scan and post it . sorry. check sonnax.com for driveline savers. designed to fail reliably.