Without seeing how the line is inside of it I would guess just a regular line fitting depending on whether it's bubble flared or inverted..... Maybe a compression of some style. Seems to me I've seen them on Mercedes engines before.
arent brass flare fittings and AN/JIC fittings have a different flare angle that makes them incompatible. i know from experience at work that a brass flare fitting wont seal well on an aeroquip JIC fitting like you would find in hydraulics and fuel systems. you may want to verify both of those fittings have the same flare angle