I needed to be add a flange end to the short side of the driveshaft so that it would bolt up the the SYE on the NP242.
Awhile back, I bought a pair of Spicer 1310 u-joints as backups, so it made sense to use them now rather than reinstall the old one. There's the flange I bought from Currie Enterprises to add to the short end.
To put it on, just use the old stand-by: two sockets, one that fits the cap size (a 3/4" one did it for me) and one that will allow the cap to fall inside it (1 1/8" for that). Your mileage may vary.
Once the first cap is out, remove it from the center cross. If you are going to reuse it, keep track of the needle bearings. The switch your sockets around, pop out the other side, and then wiggle the cross free.
Putting the flat flange on is largely the opposite of what you just did. First, mount the u-joint back on the end of the driveshaft, pulling both caps to get the cross in first. Watch the needle bearings. They should be greased in place, but one of my fell down in the bottom of the cap and got in the way of my install, but I just put it back and proceeded with due diligence. After installing it on the shaft, take the two remaining two caps off, put the flange on, and continue as before. Don't forget to add the clips to keep the cross centered in the joint.
Before I could take it to OC Driveline to get it lengthened, I took a quick measurement. From the face of the transfer case flange to the center of the u-joint on the rear differential was 45 inches. Here it is painted, balanced, and ready to go. They even added in another new u-joint on the differential end for a minimal charge (not really more than what I'd paid for the Spicer 1310 installed earlier).
Installed with red Loctite:
