Prettys sure you should be able to just get a reducer to convert the port sizes. Just look in the plumbing section at a hardware store and take the stock 6.1 sender and your old one with you. Off the top of my head I think the 6.1 port is a 3/8" NPT and the old sender is 1/8" NPT. You should be able to get a bushing that will reduce a 3/8 port to 1/8.
