If your boat works fine like it is, and its worked like this for some time, why is adding a selector valve making it right? Sounds like you're fixing something that ain't broke. 
it's not that it's broke But just cause it was "right" in 1970 doesn't mean it can't be improved!

it does draw a little more from one tank then the other I've just always kept checking but I'd like to know how long/far I can run on one tank just to gauge where I can or can't make it to I've got two 12gal saddle tanks.
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