If you are sure you need a u joint, when you pull apart the driveshaft after properly marking the flange ends you may (should?) find that the gap between two of the "male" splines is filled with an epoxy-type material that corresponds with a "missing" spline in the receiving end of the shaft, if that makes sense. It will once you separate the shafts. This is a little extra peace of mind when reassembling so that you don't put it back one spline off. It is possible to put it back wrong but it tries very very hard to tell you something's wrong.

I only mention this because I once owned a 1993 that some fool just jammed back together to keep some yokes parallel or something when they should have been perpendicular. It was a mammoth pain getting the thing separated in the first place, and they just beat the crap out of the yokes to get it back into place the way they wanted it. Fwiw the car didn't have any abnormal driveshaft vibration that I noticed so I don't know how particular the splined shaft orientation really is in practice. I put it back the right way and there was no change. The shafts should separate easily given a good dust cap seal and no rust, but your car may be a northern car so who knows there.

Might as well check the center support bearing, its rubber holder, the spring and cupped washer while you're at it too. Flex disc too if it's a stick.

Do you have the Bentley manual for the car? As I recall it is pretty detailed in its description of the r&r procedure and the correct yoke orientations on reassembly. Definitely a worthwhile investment if you plan on doing really any work on the car. Though it may seem fairly expensive it is 100% worth it.