Thank you for the quick reply, Flash75.
Last night I removed the other part of the u-joint yoke, the part attached to the flange on the transmission shaft, and it was damaged pretty badly as well so I'll have to replace it too.
I am a little confused about part of your response. I don't see how one can replace the front yoke without disassembling the sliding splined joint. It looks like the front yoke and this joint are all one unit, i.e., replacement of the yoke appears to require taking the joint apart. Now I wonder if I'm missing something???
By the way, now that I have the drive shaft off it is obvious that the u-joints weren't alligned correctly, per the link you included, when I got the car. I guess this hastened the u-joint failure.
Thanks again for you help and advice.