I've done it a couple different ways over the years. Nearly a decade ago on my old Corsica, I acquired a 1/8" NPT x 1/4" NPT pipe bushing and brazed it into a hole on the side of the pan. Then plugged it with a 1/8" pipe plug. Kinda ugly, but works just fine.
The easiest and cleanest-looking method I've come up with though is to drill a 3/8" hole through the pan- in a location with plenty of clearance inside. Tighten a nut and bolt into the hole, with the nut on the inside. Tack-weld the nut to the pan. Remove the bolt and reinstall with a copper washer. Problem solved.
One variation I did on my wife's car was to cut a 1/8" deep slot across the face of the nut, then install the nut and bolt with the slot facing toward the bottom of the pan, and a washer between the nut and the pan. Then tack weld the nut and the washer. This extra slot allows a little more fluid to drain. Not really necessary, but a marginal improvment.
The easiest and cleanest-looking method I've come up with though is to drill a 3/8" hole through the pan- in a location with plenty of clearance inside. Tighten a nut and bolt into the hole, with the nut on the inside. Tack-weld the nut to the pan. Remove the bolt and reinstall with a copper washer. Problem solved.
One variation I did on my wife's car was to cut a 1/8" deep slot across the face of the nut, then install the nut and bolt with the slot facing toward the bottom of the pan, and a washer between the nut and the pan. Then tack weld the nut and the washer. This extra slot allows a little more fluid to drain. Not really necessary, but a marginal improvment.
