[67malibu]

I just dealt with this myself a few weeks ago. I knew mine has been 'rotted' for years ('88 K1500) but just ignored it until I had to lift the engine to get the oil pan off. The nipple fell apart from a little bit of torque on the hose. I wish I had better news for you but I took some small cold chisels and was able to unscrew most of what was left back out of the threads (after an hour of standing on my head getting the right angles), polished the threads with a dremel and wire wheel then bought two new nipples. I knowingly ruined one using it as a tap to paritially straighten the threads then was only able to get two and a half turns with the good one. I'm replacing the engine this winter so I put a good dose of JB Coldweld on the threads and around the nipple since the threads are beveled. It's holding just fine and seems to be quite strong but it's not a good way to fix it except when you booger up the threads trying to get the semi-welded in remnants of the old nipple out. I would suggest going with a regular slip on connection nipple and get rid of the quick disconnect.