Should be flush with the engine case or just below. That how's mine is. Yours leaking, why did you mess with it. Just wondering, I'm on my 3rd. clutch & over 212k with no rear main leak.
Original Motor/VF-40 Turbo/15k OCI, Amsoil 0w-30 SSO & Ea. oil filters. Tuning Alliance Stage 2+, 18.5psi. Member; 200K + club. Currant mileage:299875