I have a 1997 F-150, that was in need of new u-joints. I replaced the rear u-joint with no problems. However the front has 2 u-joints and a coupler between them. When I took one of the u-joints out, the coupler came apart, and I can't figure out how to put this damn thing back together. Can someone help??

Thanks

 

That would be your "Dual-Cardan" Constant Velocity Joint.
The difference being that it takes two universal joints to make a "Constant Velocity" joint.

I'm not sure if your problem was the joint or you can't re-assemble the joint. If you go to a local dealer you can get the part nomenclature for the rebuild kit for the Dual-Cardan.
There is a rebuild kit for the CV "Spider" which is inside the Dual-Cardan.
There is a steel ball joint which paces the inner and outer universal joints. There is also a spring that rides behind the ball joint keeping it stable.
If you think that you misplaced some of the components of the dual-cardan it may be better for you to rebuild or refurbish the whole shaft with the Dual-Cardan Rebuild Kit.
While doing the refurbishment you can substitute all of the Universal Joints with "Moog" lubricator joints.