[56markII]

Sometimes you don't have any options other than after market! After 35 years of having a weeping fuel tank and from the fitting for the fuel line due to some idiot over torquing the fitting and cracking the soldered joint on my 50 Mercury I saw an exact (except for the sender grrrrrr!) reproduction from Tanks Inc. This makes me shake my head because the banana in tech support said " I have info from a reliable source that a 75 ohm sender is required". My comment is your source is BS and 30-40 ohms is proper because my system is stock 6 volts and running perfect but thanks to your bright idea of not manufacturing it to support OEM parts forced me to purchase an incorrect sender!! I spent much time tanking my original with the key on and measured the resistance at various indicated levels on the gauge in an attempt to tame this gauge! Due to the excessive resistance my tank shows the fuel level drop faster than it really is and greatly reduces the effective range of the float arm! It took many attempts of bending, adjusting the length etc. but in reality I will end up placing a resister in parallel to reduce the resistance of this sender. Get ahold of somebody who has a good sender and get resistance specs at full, empty, 1/4, 3/4 etc. and go from there. My original tank has a 6 bolt pattern and the POS replacement gauge is 5 and meanwhile other manufacturers have both or OEM options on the sender mount! When going through this mess also don't let your gauge peg excessively in one extreme or the other as well because this could damage the gauge!
Oh and if I would have totally removed the tank from the car and stood it on end my success would have been better than attempting to solder with the solder being able to flow down and off instead of on end and allowing the molton solder to pool and cool!