speedo cable leak question

Speedo is pretty simple, just pops out. Just the retainer with one bolt holding it as pictured above. Not much to the kickdown seals, but like the speedo there is an inner and outer. I did mine with everything dissasembled. Probably need to drop pan and valve body to do in car. but not sure. Outer is a reg oil seal you'll need to tap in, so may be tough to do with trans installed.

That's right, there is one in the case and one in the linkage shaft of the valve body under the C clip and washer.
The valve body does have to come out if the trans is in the car, and it isn't very easy to do unless you know what you need to do it.
To seat the new seal in the case from underneath you have to have a way of pulling it down from the top.
A slide hammer with a washer on the end works pretty good.