Heater Hose Nipples 1970-up Big Block/Hemi. This contains both nipples the 1/2" nipple has 1/2" thread some 1970's had a 5/8" hole which would require using a pipe adaptoer or also ordering 101-HNK5 which is a 5/8" threaded nipple for the 1/2" hose. Our part # 101-HNK2