I am really confused. You have a mechanic that says it is a sprague. Crosley, who has been doing this forever, says it is the 3/4 clutches, which I would bet on. And you are asking how to take it out? If your mechanic knows so much, shouldn't he know the best way to take it out?
I am with Troy, to a point. I think it needs to go to a trans shop BEFORE it is taken out of the car.
If you insist on taking it out, check some of the previous posts. There are several posts on the proceedures for doing that. Basically they are the same for most all rear wheel drive vehicles.
I know that in the last few weeks I posted the basic proceedures, and believe they were for someone with a Camaro.