Triple-jointed driveshaft?

My donor car is a 1990 Lincoln MK-VII and I'm using a 8.8" rear out of an Explorer. Why does the Lincoln drivershaft have 2 u-joints on the end by the rear end?

 

That's a double cardan joint. It is a type of constant velocity joint.

 

They let the driveshaft in the Lincoln run a little smoother at least in theory. That setup isn't needed in a hot rod though unless it just happens to be the perfect length for the installation. Among other things they are somewhat expensive to repair as compared to a driveshaft with a joint on each end.

 

Thanks for the education, guys.

 

And they are a pain to repair.

 

And, a lot of them cannot be repaired,...what is done is to cut the bad one off the shaft, and weld on a new item. The shaft is re balanced, and you buy a "rebuilt driveshaft". I learned that when I owned a 68 Caddy.

4TTRUK