Found a fuel sending unit that swaps in with little mods On my 74 (dont know which one are the same) Ordered a 65-68 mustang fuel sending unit from mustangs unlimited seen here to harvest the parts to fix mine but I didnt have toThought it was a good deal compared to the others that swap as far as money wise http://cgi.ebay.com/ebaymotors/ws/eBayISAPI.dll?ViewItem&ssPageName=STRK:MEWNX:IT&item=120394934812 Uses the same gasket (rubber seal)same diameter and shape inside the tank and at the sealing surface. I did have to modify the electrical plug (cut the factory one off and replaced with a eyelet) and re grounded the other wire to the tank body.The only big thing I noticed (which worked good for me) is the fuel outlet is facing rearward (longer fuel line should solve that for stock guys) Just wanted to share hope it helps someone like it did me.
I ran it through the paces before i installed it then checked it as i put fuel in it (5 gal can at a time were i drained the almost full tank it had,Seems to be as accurate as the other was except this one works all the time