Excessive backlash??? video inside

[93 saturn sl2]

My Mustang has a problem where if im in 1st and off the throttle at low speeds; the car will buck back and fourth until I give it gas. A friend was saying its probably u joints, but they seem to look okay. Could it be excessive backlash?

[video]http://s961.photobucket.com/albums/ae96/2002gt/?action=view&current=175cd8b5.mp4[/video]

 

[1BADAIR]

coasting or light throttle? is the car stock?

 

[93 saturn sl2]

Just does it while coasting. As soon as I give it gas the bucking stops. It has 3.73s in the rear that I had installed a few years ago. I cant remember if it did this before or not.