The problem reported with the aftermarket FR u-joints is the setscrew clamping force and backing out, so thread lock them in.
The original design is a split joint with the through bolt which has much greater clamping force. On a full round shaft these are also more easily clocked on a spline and don't have to worry about the setscrew binding on splines and burring them.
PANTERA INTERNATIONAL
A DE TOMASO CAR CLUB
Presents the De Tomaso Forums
The On-Line Meeting Place for De Tomaso Owners and Enthusiasts From Around the World
Clicking on the banner will take you to the sponsor's website.