Well there are a number of things here
1] stock mounts are not as good as in 1970 , the assy line is not using hundreds / day anymore & the batches that are being made welll ....
the last set I bought had made in India on them !
2] stock mount without a tq strap is a limited time line with disaster at the end often distroying rads fan shrouds & hoses .
3] the sneakiest way to run a strap is to go from the block ear to the cross bolt on the mount with a 1" wide steel strap virtually invisable & just as indestructable .
You need something better for sure