Oil leak out of the speedo cable mounting adapter on the tranny

I have a leak from the speedometer cable housing on the drivers side of my Torque Flite.

Who has replaced the seals / o-ring setup on that, and what is involved (which parts are required) in the remove/replacement of those items?

I vaguely recall that someone posted that it is best to jack up the car from the rear (to allow the tranny fluid to drain forward), place the car on jack stands on the rear end / frame, then disconnect the speedo cable, and use a special tool to remove the seal / o-rings? This is a two part / two - piece
replacement (inner o-ring and outer round rubber seal)???

Any info. on the steps required and the pitfalls(what to avoid-what to do), and the parts required would be appreciated!

This tranny is leaking on the exhaust pipe, drivers side! STINKS!

Tranks in advance...