I have an 87 RT4WD with bad U-Joints (on the drive shaft). As far as I can tell, no one makes this part for this car. I took a bunch of measurements and tried to find a similar one from another car. After hours of scouring spreadsheets and databases, I can confirm no other U-Joints are even close to the size of the one on an 87 RT4WD Civic. The 88-91 ones are easy to find, but a very different size.
Having a custom-made joint in a small quantity is possible but quite expensive. Before giving up and condemning the car to a FWD only fate, I figured I'd check on here and see if anyone knew of a place to get this part.