Mind if I ask why you want to convert to rear discs? Do you do much off-roading? I ask because I would not recommend rear discs if you intend to do some wheeling. The reason: Disc brakes don't function as well wet as drums do. If you encounter wet crossings and mud, you lose braking effectiveness with the rear discs. If you run strictly on the road, convert. As far as sources, I will have to look around my mags for a bit.
'75 CJ5 304cid, t18 tranny w/granny low, model 20 T Case, DANA 44 rear, 30 front, 4" suspension lift, 33" tires, in need of more work!
"The only thing necessary for the triumph of evil, is for good men to do nothing." (Edmund Burke)