UPDATE: I had this leak and did this fix last weekend. When I rocked the nipple it was loose and there were traces of dried up coolant around the base of the bong (my slow coolant leak found). I followed the instructions but it is not complete
. The barbs will break off when removing the nipple, I can't see how the poster was able to recover the barbs as they are designed to secure the nipple on the rad and to be a one time install, so when you remove the nipple they will break off. If you are going to do this it is a 5 minute job if you loosen the fan shroud and the nipple comes out intact but it will take longer if you do it properly. I would suggest draining the coolant, remove the upper rad hose and extend a rag or something that will fit in the upper rad pipe to catch the barbs when the nipple is removed.
The new nipple fits perfectly (tight), refill coolant and bleed the cooling system and you are done. This is one of the easiest fixes if you need to do it.