Re: Trans cooler fitting size?
the radiator is 5/16" inverted flare. or 1/2-20 with an o-ring. If you're splicing into your factory lines you will want the one with the 5/16" hose barb. If you are going from the fitting to a trans cooler then you will want the 3/8" barb.
As for the fuel rail, it is 4an and we have the female couplers in stock (usually sold with the 1.5" gauge) You may also consider a small piece of braided hose so the sender/gauge is not attached directly to the rail. Vibrations have been know to make the fuel rail crack.