[Mike_The_Grad]

Wow. With the condition of your old sending unit being that bad, you should disconnect all of your fuel line connections and blow them out with compressed air. Both directions. I actually pulled the steel fuel lines from the frame rails and ran some Berryman's ChemTool CarbCleaner through them until there was only clear fluid coming out. Then I blew out the lines with my air compressor. Thankfully no rusty crap came out, but it was nasty brown varnished and I think the zinc coating of the tank or the fuel lines themselves. It was a very fine grayish powder. Then I thought about the fuel filter inside my Quadrajet. That very fine sediment was inside the filter too. Also maybe change the fuel pump if you haven't already done so. The diaphragm inside the pump could be bad if the fuel running through it contained the missing parts of your sending unit float.