U joints

I had my local mechanic check the u joints on my 86 B2000 long bed with 150,000 mi.
 
They said the middle joint was bad and the rear has a catch in it and will soon need replaced.
 
They told me the only way to fix the rear joint is to replace the whole driveshaft.
 
I have a Chilton's manual that doesn't give much info about this.
 
Any information would be welcome.
 

Look up drive shaft shops in the yellow pages where u live, I've had 2 rebuilt by similiar shops.  They ended up making the u-joints replaceable but you have to be careful the one you have isn't worn too much (nothing to rebuild).