[Class of 69]

I drill and tap a 1/8 pipe thread drain plug into one of the three bosses that the converter lugs are welded onto to drain the converter. Use a brass pipe plug, as it is lighter than a steel one, for balance. I learned this from a competent trans man 30 years ago, and he did it to every trans he overhauled. Only takes an extra ten minutes the first time and allows complete changing of the fluids. It's messy to drill it the first time full, but the fluid helps flush the drill chips out, not in. If you drill it dry, fill the flutes of the bit, and tap, with chassis grease to retain the chips on the bit, and hold the converter up, so the chips fall down , not into the converter.