This is the sending unit that measures the amount of gas in your tank and relays the information to your gas gauge. Brothers sending units are constructed of high quality stainless steel. Fits the below applications: truck - rear mount gas tank79-81 350ci (79-80 auto trans)78-81 454ci blazer - 25 gallon tank78-86 305ci (78-80 auto trans, 83-86 4wd)78-86 350ci (78-80 auto trans, 81-86 4wd)78-79 400ci (4wd) suburban - 25 gallon tank79-86 305ci (1979 auto trans)78-86 350ci (78-80 auto trans)78-80 400ci78-86 454ci