I know the 3/8 is smaller, but I've heard of using the 3/8 or that it is suitable. Also on places like summit racing they state that fittings are "3/8 or 10mm" meaning they are for either or. Both lines are 3/16 so as long as the double flare mates which it does, am I good? This is a custom bent line and 10mm union fitting I'm doing for the clutch hard line delete.
Follow Ups
3/8 male clutchline fitting into 10mm female for 3/16 line? - Jkova300z15:32:10 03/08/13