727 gone bad??

Let me introduce my car and st up to y'all. I got me a 1980 bowtie Camaro but it has a 440 big block with A-727-B transmission. The tranny is a short snout so I assume its from a truck. Well I was driving it and heard a huge popping sound towards the back and was wondering what was it that we heard. Now when I drive it will a little bit and then slip. It will go nowhere. Turn the car off for a min or 2 then will go a little bit. Any ideas what's going on it what happened? Checked the fluids and its full and not burned up.
Author: camaro440